T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
V o l . I I . J U L Y , 1 910. N o . 7
T h e J o u r n a l o f I n d u s t r i a l
a n d E n g i n e e r i n g C h e m i s t r y
PU B L ISH E D BY
T H E A M E R I C A N C H E M I C A L S O C I E T Y .
BOA RD OF E D IT O R S.
E d itor:
W . D . R ich a rd so n . Associate Editors.
G eo. P . A d a m son , E . G . B a ile y , G . E . B arton , W in.
B rad y, W m . C am p b ell, F . B. C arp en ter, V ir g il C ob len tz, F ra n c is X. D up on t, W . C. E b a u g h , W in . C . G eer, W . F . H ille b ra n d , W . D . H o rn e, ¿ . P . K in n ic u tt, A . E . L e a cli, K a r l L a n g e n b e c k , A . D . L ittle , P . C. M c llh iu e y , E . B.
M cC r e a d y , W m . M cM u rtrie, J. M e rritt M atth ew s, T . J.
P a rk e r, J. D . P e n n o c k , G eo . C. S to n e , F . W . T ra p h a g e n , E r n s t T w itc h e ll, R o b t. W a h l, W m . H . W a lk e r , M . C.
W h ita k e r , W . R . W h itn e y .
P u b lish e d m o n th ly . S u b sc rip tio n p ric e to n o n -m e m b e rs o f th e A m e ric a n C h em ica l S o ciety $6.00 y e a rly .
Vol. II. JULY, 1910. N o .7
ORIGINAL PAPLR5.
THE USE OF FERRQ-TITANIUM IN BESSEMER RAILS.
B y P . H . Du d l e y.
T h e w riter calculated and tested experim entally a form ula for the use of ferro-titanium for Bessemer rails, to augm ent the average toughness and d uctility of those of 0 .50 in carbon and 0.096 in phosphorus, in connection w ith the N ew Y o r k Central Lines—
190S specifications. T h e use of Bessem er rails w ith p ractically o . 10 in phosphorus w ith as low carbon as mentioned under high-speed trains was not a m atter of choice, bu t of stern necessity. I t has been the e x pectation of Bessem er steel m anufacturers and rail
road officials for some years th a t owing to the ex
haustion of the low phosphorus ores basic open-hearth rails would replace Bessemer, as the latter replaced iron less than half a century since. Several basic open-hearth plants h ave been installed and ou t of about 45,000,000 tons of rails in our tracks 2,000,000 tons are basic open-hearth. I t was generally con
sidered a simple problem to m ake the basic open- hearth rails of even 0 .7 5 to 0.85 in carbon, bu t under 0.03 in phosphorus, and still secure im m unity from rail fractures and failures, therefore, it was expected b y the use of basic open-hearth rails th at the fractures common to Bessemer steel would be eliminated.
T h e practical results of m any fractures and failures in the new m etal modified opinion and it will require tim e for a return to the conditions of m anufacture which m ust be observed.
T h e chem ical composition of 0 .75 to 0.85 in car bon, w ith the accom panying manganese advocated a t first as safe, forms in m any cases a eutectic m ix
ture in which the ferrite is apparently all absorbed, the d u ctility of the steel being low, hard and sensi
tive to shocks. T h e saturation point of the ferrite b y carbon has been considered as 0.90, but in rails and tires w ith the manganese content it seems often ten to tw en ty points lower, and traces of cem entite m ay occur. A carbon content of 0.62 to 0 .75, with greater ductility, is considered more reliable in rails as girders.
T h e dem and for basic open-hearth rails in 1907 and 1908 was far beyond the cap acity of the plants to fill. Therefore, b u t few railroads were able to se
cure sufficient rails of th at d ass of steel for their re
quirements and others had to be content w ith a small tonnage for trial. This compelled me to "reinstate form er Bessem er principles of practice which had been lost in the great demand for output, and also to try additional means for better Bessemer rails for m odem h eavy wheel loads and high-speed trains.
I did n ot expect or consider th at m y method for the use of ferro-titanium would be generally used b y the railroads for the Bessemer departm ents of all m anu
facturers were not so arranged th at th ey could fol
low all the details but would be obliged to resort to more expensive methods.
T h e results of the first service tests seemed so satis
factory to other railroad system s th at th ey wished to try sim ilar rails and several trial orders were placed for 1,000 to 5,000 tons, distributed over a great e x tent of country. T h e rails passed through the un
usually .severe w inter of 1909 and 1910 w ith favora
ble comparisons.
I have answered m an y inquiries in reference to m y rails, b u t have been reluctant to answer requests for publication until I could h ave the results of the ser
vice of tw o winters to see whether or not th ey agreed and sustained the calculations and prelim inary phys
ical tests.
F iv e thousand tons of rails of the six-inch 100-lb.
D udley section were m ade in 1908 and sent to the E lectric Division in New Y o rk C ity. T hese rails were laid in the autum n of 1908, and in M ay, 1910, n o t a single rail had broken. T h e plain Bessemer rails in the same section and location had heretofore
300
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . July, 1910 developed a number of fractures during the winterseven for those having no higher content of carbon than the present rail in which ferro-titanium was used.
Seven thousand and five hundred tons of the same section were sent to the Boston and A lb an y R ailroad and only three rails failed, two from injuries received in loading. W hile in three thousand tons of 80-lb.
rails some of them laid in 1908, therefore, had two w inters’ service, not a rail fractured, which tends to corroborate the calculations and. prelim inary tests.
The equally as good com parative results on other railroads beside the N ew Y o rk Central lines are further confirmation th at some increase in purity, toughness and d u ctility of the m etal has been practically se
cured.
T he problem in the m anufacture of rails for high
speed trains a t the present tim e is to obtain a higher average purity, toughness and d uctility for the m etal of all the heats than was required fifteen and tw en ty years ago, before the advent of the present h eavy wheel loads and high-speed trains. T he five-inch 80-lb. rail which I first designed for the New Y o rk Central & Hudson R iver R ailroad, in 1883, the phos
phorus content was 0.0S w ith 0.45 to 0.50 in carbon.
Som e of these rails proved fragile in the track after a few years’ service under the high-speed trains which were inaugurated after the introduction of th at sec
tion. When I made the revised 5 l/a in. 80-lb. and six inch joo-lb. sections, and also the Boston & A lb an y 95-lb. section in 1890, I knew from experience th at it would be necessary to increase the carbon content o f those rails for h eavy service. T o do this I limited the phosphorus to 0.06 in the m etal and m ade the carbon content 0.56 to 0.65 in the Boston & A lbany 95-lb. and the 100-lb. rails. These proved under the drop test to be not only tough, but the d uctility ranged from 10 to 14 per cent, as secured for the m ost of the heats.
T o m ake and test the rails in 1891 I had to re
instate the drop test and made it a part of the speci
fications th at 90 per cent, of the butts should stand a drop of 2,000 lbs. falling 20 feet, supports three feet apart, and heats of butts which broke, though gave four per cent, m axim um elongation per inch, would be accepted. T h e butts before testing were stam ped in the center on the base or head, as desired, w ith a spacing bar of seven conical points, each one inch apart. These six-inch former spaces after the drop would be extended and were measured b y a flexible steel rule divided in hundredths of an inch, therefore, the excess hundredths per inch gave the percentage of elongation. T h e range of d u ctility of the steel was designed to be between 8 and 15 per cent., excepting the small percentage of heats of which the minimum elongation m ust be 4 per cent, or over to be accepted.
T h e m axim um elongation per inch for the 100-lb.
rail under the 40,000 foot pounds of energy of the drop was only five per cent, for its standard perm anent set of 0.92 of an inch. Therefore, m ost of the energy of the drop would be expended upon the b u tt when the four per cent, elongation was produced per inch before the b u tt broke or sheared.
A shear was not treated as a broken b u tt in the re
jection of heats for the valuable indications it gave were th a t the upper lim it in chem ical composition for a fine textured steel had been p ractically reached.
The elongations were measured and considered in ac
cepting or rejecting the heats. I t takes b u t a few m inutes now to describe the earlier results in the heavier sections, b u t it was the work of years, first m aking the steel, rolling the sections, then taking yearly diagram s of the tracks b y m y T rack Inspec
tion A pparatus, and also studying the results of serv
ice for guidance in future work.
There were over 600,000 tons of the low phosphorus, 0.06, and high carbon rails m ade and in m ost of them the copper content ranged from 0 .6 to 0 .8 of one per cent., which, after the long service, is considered to have added to the toughness of the steel under the passing wheel loads as b u t a small percentage of the rails have broken after tw elve to eighteen years of service. Since the exhaustion of the low phosphorus ores and the loss of the copper in the Bessem er rails for the same section, a greater decrease, proportion
ately, of the carbon has been required for the four additional points above 0.06, or o .x o phosphorus in the m etal. T h e minimum range of d u ctility for the higher phosphorus w ithout copper m ust be six to- seven per cent, instead of the former minimum of four per cent, w ith copper.
T h e high phosphorus content of 0 .10 constitutes the greatest objection to-day to the use of such Besse
mer rails for h ea vy traffic and is one reason w h y I am trying to m ake them better b y the use of ferro- titanium .
Phosphorus m akes steel brittle to shocks as it hard
ens it, w hich lim its the carbon to about o . 50 for h eavy sections, where th ey are to be used in tem peratures which fall io ° —20° F. below zero in the winter months.
The brittleness in the early Bessemer steel rails was attributed principally to the phosphorus content even w ith the low content of 0.30 to 0.40 carbon. I t seemed to be erratic, or such effects were attrib uted to phosphorus, for it was found to exist in two or more forms in the steel, one form being considered harmless and another detrim ental. This is not con
sidered proven in practice, as all high phosphorus m etal in rails has fractured more than low phosphorus Bessemer rails. T h e early sections of steel rails were rolled only 3V2 inches to 41 /4 inches in height from small ingots and segregations of carbon and phosphorus were elongated and diffused more than is the case of heavier rails from large ingots.
D U D L E Y O N T H E U S E O F F E R R O - T I T A N I U M I N B E S S E M E R R A I L S . 301 Sections of 52-lb. rails, which wore well under the
light service, though some rails fractured, have been found recently which contained 0 .1 4 and 0 .1 6 phosphorus in tw o different brands of rails. These light sections had small m echanical properties, were flexible in the track and could not carry large bend
ing moments, therefore there was more tim e to dis
tribute the strains of the passing wheel loads through the m etal of the section than there is in the present heavy stiff sections, carrying larger bending moments to reduce the undulations and train resistance of the track.
The first experim ents of the use of ferro-titanium in the m etal the ingots were better and the steel showed an increased purity, toughness and d uctility.
The same carbon content com pared w ith the plain Bessemer steel in the same sections the d uctility averages higher and runs more uniform for a larger number of heats than it has been possible to secure in ordinary Bessemer. T h e ferro-titanium as a sub
sidiary deoxidizer, besides reducing a greater per
centage of oxides of iron in the steel, also reduces a portion of the nitrogen, which decreases the b rittle
ness and thus adds to the toughness of the steel.
The nitrogen content seems to be small in some heats, but higher in others, and b y the use of ferro-titanium a more uniform range of d uctility has been obtained in the steel.
T he nitrogen content reported in some of the 1904 Bessemer rails which broke was 0.0 147 to 0.0153, and in others which did n o t 0.003 to 0.006, accord
ing to determ inations w hich I had m ade in 1906.
These were considered as com parative indications rather than as accurate determ inations which can now be readily and more cheaply made. I t is con
sidered as a working hypothesis th at the nitrogen con
tent in steel reduces the d u ctility five times faster than phosphorus and fifteen times faster than carbon in large sections of rails subjected to shocks. These comparisons w ill be checked for rectification as data is gathered in reference to nitrogen. T h e use of ferro-titanium shows a reduction of the nitrogen con
tent in steel after its use and an increase in the tough
ness, besides a greater reduction of the oxides of iron.
'P lo ttin g th e.resu lts of the elongation of the drop tests has been of invaluable service to me in rail m anufacture for high-speed trains. T h e d uctility o f the steel in the full-sized section can be exhausted in two or more blows under the present M anufactu
rers' Standard Drop T estin g Machines, the b u tts be
ing stam ped in inches before testing, as already de
scribed. The elongation of the m etal under the drop testing machine compares fa vo rab ly w ith th at obtained b y static loads in the testing machine. The tendency is an increase of possibly two or more per cent., owing to the fa ct th at the base of the rail w hich.
stretches does not neck as in the case of a tensile specimen. I t is also probable th at the energy con
verted into heat, and the rising tem perature of the bu tt, under successive blows, slightly increases the d u ctility of the metal. T h e possibility of deter
mining qu ickly the d u ctility of the m etal in the sec
tion from hour to hour as rolled is one of great value, as conditions of m anufacture can be followed as they occur.
A 100-lb. rolled section of pure iron, before ex
haustion of ductility, would show under the drop an elongation of 45 or 50 per cent, for two or three inches d irectly under the point of im pact. B y adding car
bon and manganese to the iron, increasing the phys
ical properties of the m etal, there is, as expected, a ’ reduction in the elongation of the m etal. T h e con
tent of impurities of phosphorus, sulphur, nitrogen, arsenic and oxides th a t will m ake further reductions of elongation and should be considered in the chem ical composition for service as girders or to harden the m etal to resist abrasion for slow trains.
Fig. 1 shows a chart of the records plotted of the drop tests of 224 heats of 90-lb. Bessemer rail A . S. C. E- Section, rolled in March, 1910. T he hori
zontal lines on the charts w ith their figures indicate 30--C
i ... - .... " " ~\
\
!? 5? i
10
7
0 0 0 !.l 0 * /60 eo 0
F ig . 1.—C o n secu tiv e d ro p te s ts . 90-lb. R ails. A. S C. E . S ectio n . B essem er: C, 0.44; M n, o 90; P , o 095; Si, 0.13.
the percentages of the elongation and d u ctility while the vertical lines and figures the heat numbers. T h e chem ical composition of the steel averaged 0.44 in carbon and 0.096 in phosphorus, the manganese being nearly one per cent. These rails were intended for a high average range of d u ctility as girders and therefore are on the soft side for wear.
T h e m axim um elongation per inch under the drop of 2,000 lbs. falling 17 feet was 7 per cent. The elongation for a single blow for all the heats is definite, for each b u tt withstood the drop and retests were not required in a single case. This percentage is shown b y a line of dashes and dots m arked 7 per cent.
Therefore, the minimum d u ctility of e very heat is above the 7 per cent. line. There were thirteen of the butts distributed through the heats and the duc
tility exhausted com pletely to find the m axim um for the m etal. These are plotted on the charts b y a line of dots w ith circles, the latter to indicate the heats which were tested.
30 2 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . July, 1901 I t is not possible in regular work of the mill to have
the drop testing machine sufficient time to exhaust the d u ctility in every heat, but only of a few to show the elongation in the general run of the steel. I t is probable that there would be some heats which were not exhausted com pletely th at the minimum duc
tility would be less than the 12 per cent, shown for the five heats, b u t it would be above 7 per cent.
E ach of the five heats, beside standing the first blow, required a second to break them, the elonga
tion being about 12 per cent, and is shown b y a hori
zontal line of short dashes. The two circles in the first group of 40 heats indicate there were two tests which required five blows to exhaust the 28 per cent, ductility, and then a heat broke under two blows with the 12 per cent, elongation. Three butts in each of the following groups of 80 heats also gave 23 per cent, ductility. T h e following 15 heats are repre
sented b y two butts which broke a t the second blow, but each gave about 12 per cent, elongation.
The plotting of the group in this manner is to ob
tain a general indication of the elongation and duc
tility during a turn of tw elve hours, or two turns in tw enty-four hours’ work, and this is above the average for Bessemer rails.
T h e charts of the drop tests plotted in this m an
ner show positively the ductility of every heat secured b y one blow of the drop, and of the others in which th e d uctility is com pletely exhausted. W hile the permanent sets under the drop have been recorded, it has not been usual to measure the elongation of the m etal per inch in the section except in m y prac
tice.
T o compare the d uctility of individual heats or melts, tests are m ade exhausting the d u ctility b y tw o or more blows. These are shown b y Figs.
2 to 7, inclusive. The graphic representation of each heat of m elt in the figures is shown, as will be seen, from the percentage m arks per blow and are represented b y vertical lines of about one-fortieth of an inch (1/40") in thickness; two blows double th a t thickness; three blows three times; and four blows b y one-tenth of an inch (1/10"). The different steps shown on the chart gives the percentages of d uctility obtained a t each blow, w hile a double width of the top indicates th at another blow was required to break the butt, though additional elongation was not produced. T h e horizontal lines in the diagram s w ith their figures indicate the percentages of elonga
tion.
Fig. 2 shows elongation and ductility tests of plain Bessemer steel rolled June 14 and 15, 1909.
The heats Nos. 14793 and 14925, represented b y the first and second graphs, were tested March 28, 1910, drop 17 feet. T h e steel was intended for a range of d uctility of 10 to 15 per cent, and required three blows of the drop to break the butts.
T h e heat No. 31703, represented b y the third graph, was rolled Septem ber 18, 1909, and tested March 28, 1910, drop 17 feet. T he object of holding these butts was to see about the rem oval of the initial
I E
F ig . 2.— D u c tility te s ts . 100-lb. ra ils, D u d le y Sectio n . B es s e m e r: C, 0.50; M n, 1.00; P, 0.096; Si, 0.13.
strains of rolling after six to eight m onths of m anu
facture. T h e b u tts were reserved on skids under cover a t the m ill but had not been handled. I t had been noticed several times th at groups of butts which stood the drop test on the d ay of m anufacture or a d ay thereafter, th at when some were laid aside on the ground four or five weeks they did not stand the drop test, but some of the same butts, after three to six months, usually stood the test, the belief being th a t the initial strains of rolling had b y tim e become better equalized. I cite this as a coincidence which occurred w ith the author twice, and others h ave had similar coincidences, but these do not establish a general law , as the manner of storing is now believed to be an im portant factor.
New steel rolls, after turning to dimensions, are safer from breaking b y “ seasoning” six to eight m onths before using, for a large am ount of m etal has been removed from the exterior diam eter and the interior strains require tim e or change of tem pera
ture to become equalized.
Fig. No. 3: H eat Nos. 17571 and 17575, repre
sented b y the first and second graph, were rolled June 1, 1909, for the D etroit R iver Tunnel Co.
These had a discard of 19 per cent, and were tested March 29, 1910. '■< T h e third ■'"graph was the same
~
F ig . 3.—D u c tility te sts, ioo-lb. ra ils . F. T . B essem e r: C, 0.50; M n, 1.00; P , o 095; Si, 0.13.
section rolled M ay i, 1909, b u t tested the_ same d ate as the others. These were ferro-titanium rails to have a range of 15 to 20 per cent, ductility'. Height
D U D L E Y O N T H E U S E O F F E R R O - T I T A N I U M I N B E S S E M E R R A I L S . 303 of drop 17 feet. T h e section was the A. S. C. E.
100-lb.
It did not m ake any difference when these butts were tested, th e y proved tough and a t any tim e re
quiring five blows fo r 't h e first two and six for the third, which was a 9 per cent, discard three-rail ingot.
The other tw o ingots were from the same molds bu t three-rail ingots w ith more discard.
Graphs fourth and fifth show the B and C rails of heat No. 39926. T h e B rail required three blows to break and had 14 per cent, d uctility. The C rail required four blows and had a d u ctility of 18 per cent. These were 100-lb. rails w ith a chem ical composition to have a range of 10 to 15 per cent, ductility. The sixth graph was a condemned A rail for a blistered web. The in got was delayed in charging into the reheating furnace until a large shrinkage ca v ity formed and the section failed the second blow from mechanical weakness, due to the shrinkage ca vity.
It stood the one required blow, therefore would not have been detected excep t for the blistered web.
A n y interruption to the regular mill practice as an
* F ig . 4 — D u c tility te s ts . SVa-incb 80-lb. ra ils , D u d le y S ectio n . F . T . B essem e r: C, 0.49; M n, 0.96; P, 0.096; Si, 0.13.
ingot car off the track, a “ stick e r” a t the “ stripper,”
or an extra run to the gan try, will affect the setting of an ingot or a heat of ingots, more decidedly the greater the p u rity of the steel.
F ig. No. 4 represents the D udley section of 5 1 /s inch 80-lb. rails, rolled from four-rail length ingots which are about 350 lbs. heavier than the three-rail length for the 100-lb. rails, w hile the chem ical com position is p ractically the same, the range of duc
tility being only 10 to 15 per cent, to resist curve abrasion. Ferro-titanium raised the minimum duc
tility b y three to four per cent, in these rails.
T h e heat No. 8704 shown b y the first graph was condemned b y the m aker on account of being too high in carbon, y e t it shows 9 per cent, of ductility.
I t would h ave been an excellent rail to resist abrasion upon curves under slow traffic. The other tw elve heats from No. 16195 to 16224 were aN rolled March 29, 1910, and tested A pril 14th. The low est range is 10 per cent, d uctility, while the m ajority show over 18 per cent., one heat showing 25 per cent., all heats requiring two or more blows of 16 ft. to exhaust the- d uctility. T h is wide range is interesting and reflects
the change from a medium rolling tem perature to one a few degrees lower, b y a reduction of ductility, though in none of the exam ples below the safe lim it of 10 per cent, elongation and required two blows to break the butts. Fig. 5 shows heats of plain Besse-
Pig - 5 —D u c tility te sts.
100-lb. ra ils , A. S. C. E . S e c tio n . B essem er: C, 0.50; M n, 0.98; P, 0.96; Si, 0.13.
mer steel in ioo-lb. rails intended for a range of 10 to 15 per cent, ductility. T w o of the heats gave only 7 and 8 per cent, elongation under two blows each, a third n per cent, elongation for the second blow, w hile one heat gave 18 per cent, elongation and required four blows to break the b u tt. These were nearly consecutive heats and show quite a range in the d u ctility often observed in plain Bessemer steel.
F ig. 6 shows the elongation and d uctility of ioo-lb. N ew Y o r k Central rails, D udley 6-inch 100-
F ig . 6.—D u c tility te s ts , ioo-lb. ra ils , D u d le y S e c tio n .
F . T . B e sse m e r: C, 0.50; M n, 1.00; P, o 096; Si, 0.13.
lb. section. These were designed for a range of d u ctility of 10 to 15 per cent. A ll of the heats re
quired three blows to exhaust the d u ctility and none broke under 11 per cent, elongation.
F ig. 7 shows a num ber of heats of open-hearth
F ig . 7.— D u c tility te s ts , ioo-lb. ra ils , A. S. C. E . S e c tio n . B O. H ,: C, 0.68; M n, 0 .86; P, 0.012; S i, 0. 10.
304 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . July, 1910 rails with carbon about 0.69 w ith the phosphorus
under 0.03. These were intended for a range of ductility of 12 to 18 per cent, for use under high
speed trains where the tem perature in winter falls 10 to 30 degrees F . below zero. R ails of similar composition have been in service three and four years w ith com paratively few fractures.
Correlation of the Equipment and the Tracks.
The equipm ent and track are of necessity so inti
m ately correlated that for high-speed trains of h eavy loads the wheels need tires of higher physical proper
ties and maintenance than form erly required. The tires under the h eavy wheel loads do not all wear uni
form ly the entire circumference of the tread, soft spots developing in a portion and the wheels be
come eccentric, increasing the dynam ic shocks upon the rails each revolution. The m etal in tires under the h eavy loads and high-speed trains is more severely strained and abraded than in the past, and it -«dll require as thorough consideration of the com para
tive methods of m anufacture as has been exercised for rails.
The tonnage upon the tread of a tire accum ulates w ith great rapidity. The 36-inch wheel makes 560.2 revolutions- per mile, therefore, every portion of the m etal of bearing surface of the tread is subjected to its static lead 560.2 times per mile, and for a static load of five tons it would be equivalent to 2,801 tons per mile, beside the generated wheel effects.
T h e accum ulated tonnage exclusive of the genera
ted wheel effects for a static load of five tons per wheel in a trip from Boston to Chicago would be 2,865,423 tons; New Y o rk to Chicago, 2,700,164 tons; New Y o rk to St. Louis, 3,243,558 tons; New Y o rk to Cincinnati, 2,478,885 tons. A tender wheel with an average static load of nine tons, or 5,041.8 tons per mile, the tonnage for a trip of 150 miles would be 756,270 tons and run in about three hours and fifteen minutes. The generated wheel effects would be from 20 to 50 per cent, additional in all cases, depending upon how smooth or even the treads m aintained their circumference, speed, and also the smoothness of the track. A tender wheel became eccentric for a space of about ten inches in the tread after it had run 29,000 miles and its total tonnage approxim ated 146,000,000 tons in about six m onths’
service. Some tires become eccentric after running 10,000 to 15,000 miles. The tires are subject to greater tonnage than rails in a given length of time.
Y e ars are required for the rails to carry as h eavy tonnage as the tires do in a few months, the latter being returned for further d uty. It requires a m etal of high elastic lim its of the steel to sustain the treads w ithout undue wear.
CONCLUSIONS.
i. T h e illustrations of the elongation and d uctility
tests indicate the possibility th at from a well studied chemical composition for steel rails w ith good fabrica
tion a range of d u ctility in reference to great tough
ness can be prescribed for the different sections to meet conditions of service as girders for high speeds, or w ith more hardness but less ductility, to resist curve abrasion and w ear a t slow speeds.
2. R ails which are to be used in low tem peratures under high-speed trains the toughness and ductility of the m etals m ust have preference over hardness, particularly of th a t high in phosphorus, as the la t
ter lim its the am ount of carbon which can be used to resist abrasion and wear, and still be safe as girders.
3. The carbon in basic open-hearth rails should be below the eutectic m ixture of the chem ical composi
tion for high-speed trains, as otherwise the toughness and d u ctility m ay be reduced to a condition of brit
tleness in m any rails.
4. The average ductility in Bessemer rails of 0.50 carbon and 0.095 in phosphorus has been raised two or three per cent, b y the use of ferro-titanium in the steel as practically shown b y one and two w inters’
service, and is considered w orth y of further trials.
Ferro-titanium has a direct action upon the puri
fication of the m etal and setting of the ingots, and must, therefore, be used w ith a knowledge of w h at is desired, to secure the best results.
5. T h e problems ojf rail-m aking for service in the U nited S tates are now upon a better basis than ever before, owing to the cooperation of the railroad com panies and the m anufacturers to secure rails which are suitable for the present traffic. This arises from a more general knowledge of w h at is .required than was understood a few years since.
[Co n t r i b u t i o n f r o m Pi t t s b u r g La b o r a t o r y, Te c h n o l o g i c Br a n c h, Un i t e d St a t e s Ge o l o g i c a l Su r v e y. ]
SOME VARIATIONS IN THE OFFICIAL METHOD FOR THE DETERMINATION OF VOLATILE
MATTER IN COAL.
By A . C. P l E L D N E R A N D J . D. Ü A V I S. 1 R eceived M ay 13, 1910.
In view of the proposed revision of the official methods of coal analysis, it m ay be of interest to present certain experim ental data bearing on the present official method for the determ ination of v o la
tile m atter in coal.
These experim ents were conducted in the Pittsb urg and W ashington laboratories of the U. S. Geological Survey, prim arily to ascertain the difference in vola
tile m atter produced b y using a 20 cm. natural gas flame as compared w ith the 20 cm. coal gas flame.
A fter starting the work it was found desirable to in
vestigate the influence of other factors such as gas
■pressure, typ e of burner, and surface condition of
1 P rese n ted l?y perm ission o f th e D irector, U . S. G eological S u rv ey
r i E L D N E R A N D D A V I S O N V O L A T I L E M A T T E R I N C O A L . 305 platinum crucible, i. e., dull gray or polished. In
order to elim inate influence of variation in size and shape, three 30-gram platinum crucibles of practically the same cap acity and w eight w ith closely-fitting covers were used in all the experiments, it having been dem onstrated b y actual trial th at each one of the three crucibles gave the same results.
A s these crucibles had been regularly used for vola
tile determ inations, both inner and outer surfaces had the dull gray appearance which platinum as
sumes when heated several times in the natural gas flame. T o protect the flame from air currents, the platinum triangle supporting the crucible was en
closed in a cylindrical sheet m etal shield, lined w ith asbestos, 15 cm. long and 7 cm. in diam eter, the platinum triangle being placed 3 cm. below the top of the shield; the bottom of the crucible was ex a ctly 8 cm. above the mouth of the burner.
The tem perature measurements were taken on a parallel test, using the same crijcible w ith the regular cover replaced b y one of nickel; the thermocouple, inserted through a small opening in the cover, was placed 2 mm. above the bottom of the crucible; the opening around the therm ocouple leads was closed with a cem ent of barium sulphate and sodium sili
cate.
T he description of coals tested is given in the fol
lowing table:
Ta b l e I .
Coal N o. T y p e . L ocality.
1 S cm ib itu m in o u s P o c a h o n ta s, W . Va.
2
3 **’
10 11 12
4 B itu m in o u s P en n sy lv an ia
5
6 *'
7 A n th ra c ite "
Influence of Change in Gas Pressure.— Coal gas can be burned efficiently a t low pressures, two to three inches of w ater being sufficient; natural gas, owing to the much larger proportion of air required, m ust be supplied to the burner a t higher pressures.
T able II gives results obtained b y varyin g the pressure from 1 to 13 inches of w ater:
Ta b l e I I . — In f l u e n c eo f Ga s Pr e s s u r eo n Vo l a t i l e Ma t t e r. N a tu ra l gas; T y rell b u rn e r; 20 cm . flame.
M ax
G as pres- P e r cent, v o latile m a tte r. im um
| sure in te m p e r
inches of Coal Coal Coal a tu re .
w ater. N o. 1. No. 3. N o. 6 . 0 ° C. K in d o f flame.
1 15.4 15 .8 3 2 .4 760 Y ellow tip p e d
2 15.2 16.7
3 15.4 16.7 3 2 .3 780 F a in t yellow tip
4 16.3 3 2 .7
5 16.7 16.5 3 2 .6 800 Y ellow tip ju s t re m o v e d
6 17.2 1 6.7 3 3 .0 L ong in n e r cone
S 16 .7 3 2 .7
9 17.2 825 W ell defined in n er cone
12 17.2 16 .9 3 2 .7
13 17.1 17.1 3 2 .5 845 Sh a rp , greenish, inner
cone
T e m p e ra tu re d u rin g v o latile d e te rm in a tio n on coal N o. 1 w ith v a ry in g pressures. (T im e in m inutes.)
P res
sure in
inches 0 .5 1 1 .5 2 2 .5 3 3 .5 4 4 .5 5 6 7
w a ter. ° C. ° C. ° C. ° C. ° C . ° C . ° C. ° C . ° C . ° C . ° C. ° C .
1 180 450 590 670 725 745 750 755 760 760 760 760
3 185 440 590 670 740 760 770 780 780 780 780 780
5 180 450 605 710 765 790 800 803 803 802 800 800
9 220 480 635 720 775 805 815 820 820 823 823 823
13 320 550 690 780 825 840 848 848 84S 848 847 845
T h e maxim um tem perature varies from 760 to 845° C. Coal No. 6, a bitum inous coal, gives prac
tically the same yield of volatile m atter throughout the series. The semi-bituminous coals, Nos. 1 and 3, are more sensitive to variations in tem perature, the extrem es being nearly 2 per cent. The m axim um pressure, 13 inches, was used in all subsequent work w ith natural gas.
I t has frequently been noted b y the writers that during the early part of the 7-minute volatile process, the coke swells or puffs up to the lid of the crucible, oftentim es raising it slightly. On com paring such determ inations w ith duplicates th at did not swell, th ey were invariab ly found to be one to two per cent, lower in volatile m atter. This peculiar swelling has been noticed only in the case of semi-bituminous coals. I t is more a p t to happen a t the lower tem peratures, and when the coal is kept perfectly level in the bottom of the crucible. T h e swelling can be prevented b y sim ply tapping the crucible on one side so as to settle the coal in an inclined position across one corner of the bottom of the crucible, thus pre
venting the form ation of a film of fused coal across the crucible. Com parative results are given in the following table:
Ta b l e I I I . — Va r i a t i o n s Du e t o Sw e l l i n g o r Pu f f i n g Up o f Co k e i n Cr u c i b l e.
Coke residue in
c o m p act lu m p Coke residue Coke residue
in b o tto m of sw elled h a lf swelled up
Coal N o. crucible. w a y to cover. to cover.
16.7 16.2 15.3
17.2 16.8 14 .8
* 1 17.1 16.0 15.2
15.5 15.1
....
1 5.7 15.71 5 .6
----
------
A verage, 17 .0 16 .0 15.3
2 1 7.0 15 .4 15.4
16 ,9
Influence of Type of Burner.— I t is reasonable to expect some lack of uniform ity in volatile results where w idely different types of Bunsen burners are used. A burner w ith a large bore will give a larger flame volum e, w ith a correspondingly increased heating effect. Determ inations were m ade w ith the following types of burners on both natural and coal gas:
(а) T h e sim ple B unsen b u rn e r, b o re 9 m m . (б) T h e T y re ll1 b u rn e r, bore 9 m m .
(c) T h e F letch er, N o. 5g .J b u rn e r, bore 12 m m .
* E im er & A m end catalo g , p . 80.
3o6 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . July, 19 io T h e results are given in T ab le IV .
Ta b l e IV .—In f l u e n c e o p Di f f e r e n t Ty p e so f Bu r n e r s. Difference.
P e r cent, volatile. F le tc h e r F le tc h e r
a n d an d
Coal No. F letch er. Tyrell. B unsen. Tyrell. B unsen.
(a) N a tu ra l gas.
1 17.2 1 7 .0 1 5.7 — 0 .2 — 1.5
2 17.0 16.8 15.8 — 0 .2 — 1 .2
6 3 2 .8 3 2 .6 3 2 .6 — 0 .2 — 0 .2
4 3 1 .8 3 1 .3 3 1 .2 — 0 .5 — 0 .6
5 3 1 .5 3 1 .5 0.0 . . .
A verage, — 0 .2 — 0 .8
T eiup. °C, 850° 850° 790°
(6) Coal g as (P itts b u rg ).
1 17 .0 16.7 16.3 —0 .3 — 0 .7
6 3 3 .0 3 2 .3 — 0 .7
5 3 1 .7 3 1 .4 • —0 .3 . . .
Average, — 0 .4
Tem p. °C. 855° 810°
(a) C arb u re tte d w ater g as (W ashington).
1 18.3 17.2 — 1 .1
II 18.6 17 .8 — 0.8
12 18.0 17.7 — 0 .3
10 18.7 18.4 — 0 ,3
i 18.8 18.5 — 0 .3
2 18.2 17 .6 — 0 .6
A verage, — 0 .6 Tem p. °C. 970 •
Ta b l e V,—Te m p e r a t u r e Me a s u r e m e n t s. (°C.) 20 cm . flam e; n a tu ra l g as a t 13 inches w a ter pressure.
T im e in m inutes. 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6 7 F le tc h e r b u r n e r .
coal, No. 1... 280 590 710 788 830 845 850 850 850 850 850 850 T y rell b u rn e r, coal
N o. 1 ... 250 530 670 7S0 825 840 850 850 850 850 850 850 B un sen b u rn e r, coal
No. 1... 250 580 700 760 780 785 785 785 790 790 790 790 P ittsb u rg coal g as a t 2 .5 in. p re ssu re ; 20 cm . flame.
T y rell b u rn e r, coal
N o. 1... 260 540 680 760 810 835 850 855 855 855 855 S55 W ash in g to n illu m in atin g g as a t 2 .5 in. p re ssu re ; 20 cm . flame.
F letch er b u r n e r .
Coal N o. 1 ... 630 . . . 910 . . . 975 . . . 975 . . . 970 970 970
The Fletcher burner gives slightly higher volatile m atter than the T yrell w ith practically the same m axim um tem perature. T h e larger flame volum e of the Fletcher burner, heats up the crucible more rapidly, which increases the gas yield slightly. W ith the use of natural gas, the m axim um tem perature of the Bunsen burner is 600 less than either the Fletcher or T yrell; this produces a m arked difference in vo la
tile m atter in the case of the semi-bituminous coals.
E vid en tly a burner like the Fletcher or T yrell, ad
m itting of both gas and air regulation, is preferable to the simple Bunsen.
Influence of Composition of Gas.— In order to de
termine the influence of composition of fuel gas, de
terminations were m ade over 20 cm. coal gas flame and 20 cm. natural gas flame, each gas being supplied to the burner a t its proper pressure.
T h e natural gas analyzed as fo llo w s:
C arbon dio x id e ... 0 .1 P araffin h y d ro c a rb o n s... .... 9 8 .6 N i t r o g e n . ., ,. ... 1.3
1 0 0 .0 0
T h e coal gas1 a n a ly zed :
U n sa tu ra te d h y d ro c a rb o n s... 7 .5 C arbon d io x id e... 1 .5 O x y g en... 0 .2 C arb o n m o n o x id e ... 8 .9 M e t h a n e ...•... 4 4 .8 H y d ro g e n ... 3 3 .7 N itro g e n ... 3 .4
1 0 0 .0 0
B oth series of volatile determ inations were m ade b y the same analyst, using the same apparatus, the only difference being in the fuel gas used. T h e re
sults are shown in T ab le V I :
Ta b l eV I.—Di f f e r e n c e Du et o Us i n g Na t u r a lo r Co a l Ga s. P e r cen t, v o latile.
C oal gas, N a tu ra l gas,
Coal N o. 2 .5 in. p ressure. 13 in. p ressure. Difference.
(a) F le tc h e r b u rn e r.
1 1 7 .0 17.2 + 0 . 2
2 17.1 17 .0 — 0 .1
6 3 3 .0 3 2 .8 —0 .2
4 3 1 .5 3 1 .8 + 0 . 3
5 3 1 .7 3 1 .5 — 0 .2
A verage, . 0 . 0 (6) T y rell b u rn e r.
1 16.7 1 7 .0 + 0 . 3
6 3 2 .3 3 2 .6 + 0 . 3
4 3 1 .6 3 1 .3 — 0 .3
5 3 1 .4 3 1 .5 + 0 . 1
7 4 .5 4 .3 — 0 .2
A verage, + 0 .0 4
T e m p e ra tu re °C., 855° 850°
T h e tem peratures are practically the same and the variations in volatile m atter average zero. I t should be noted, however, th at the natural gas was supplied to a carefully regulated burner a t 13 inches pressure.
I f the comparisons were m ade a t the lower pressures usually found in laboratories, the results b y natural gas would be decidedly lower.
T able V I I gives a comparison of volatile m atter obtained on the same samples of coal, in two differ
ent laboratories of the Geological S u rvey. T h e P ittsburg laboratory used natural gas a t 13 inches w ater pressure w ith a T yrell burner; the W ashington laboratory used illum inating gas a t 2 inches pressure w ith the Fletcher burner. T h e height of flame was 20 cm. in each case:
Ta b l e V I I.—Co m p a r i s o n o f Re s u l t s Ob t a i n e d i n Di f f e r e n t La b o r a t o r i e s.
P e r c en t, v o latile m a tte r.
P ittsb u rg . W ashington.
N a tu ra l gas. Illu m in a tin g gas, 13 in. p ressure. 2 .5 in. p ressure.
C oal N o. T y rell b u rn e r. F le tc h e r b u rn e r. Difference.
1 1 7 .0 18.3 + 1 . 3
2 1 6 .8 18 .2 + 1 . 4
3 1 7 .0 18 .8 + 1 . 8
4 3 1 .3 3 2 .5 + 1 . 2
5 3 1 .5 * 3 2 .6 + 1 . 1
6 3 2 .6 3 3 .4 + 0 . 8
7 4 .3 5 .3 + 1 . 1
10 17.7 18 .7 + 1 . 0
A verage, + 1 . 2
T e m p e ra tu re 850° C. 970° C.
1 Coal g as ta k e n fro m th e m ain s of th e gas c o m p an y th a t supplies, artificial gas, in P ittsb u rg . Pa,
F I E L D N E R A N D D A V I S O N V O L A T I L E M A T T E R IN C O A L . 307 From the previous experim ent on natural and
coal gas, closely agreeing results would be expected.
Such, however, was not the case. A s shown in the table, the W ashington series averaged 1.2 per cent, higher than the Pittsburg. T h e maxim um tem pera
ture of 970° C., noted in the W ashington laboratory, was 1200 higher than noted w ith either coal or natural gas a t the Pittsb urg laboratory'. I t had been sup
posed th at the W ashington illum inating gas was of a sim ilar composition to th at of the Pittsburg coal gas. This assum ption, however, proved to be erro
neous, as shown b y the following analysis:
Ta b l e V I I I .— An a l y s i s o p Wa s h i n g t o n Il l u m i n a t i n g Ga s. P e r cent.
C arbon d io x id e .. . . ; ... 3 .0 U n sa tu ra te d h y d ro c a rb o n s ... 10.4 O x y g en ... 1 .0 C arb o n m o n o x id e ... 2 7 .6 M eth a n e ... 19 .0 H y d ro g e n ... 3 3.1 N itro g e n ... 5 .9 1 0 0 .0
The W ashington gas consists entirely of carburetted w ater gas. I t contains 26 per cent, less m ethane and 19 per cent, more carbon m onoxide than coal gas. T h e replacement of m ethane b y carbon m on
oxide decreases the flame volum e ve ry m aterially, and since the height of flame is the same in both cases, the heating effect of a low m ethane gas is, under ordinary laboratory conditions, considerably greater.
Chikashiga and M atsum ato1 call attention to the disadvantages of uncarburetted w ater gas as a lab oratory fuel on account of the high tem perature of the flame produced. T h e y state th a t “ com para
tiv ely thick copper wire and sheet, and even thin platinum wire, are easily melted and hard glass easily worked in its flame.”
A nother factor th at m ay have contributed to the difference in tem perature noted in the two labora
tories is the surface condition of the platinum cruci
ble. Constam, in a paper2 com municated to the Seventh International Congress of Applied Chemis
try, mentions “ th at the slower rise and the lower final tem perature in dull platinum crucibles caused the yield of coke in them to ‘be greater than in pol
ished platinum crucibles.”
A s the crucibles used in all the experim ents a t the Pittsb urg laboratory were ve ry dull and tarnished in appearance, it was decided to polish them and then run some determ inations to check Constam ’s conclusions. T h e results are given in T able I X :
Ta b l i ï I X . — Co m p a r i s o n o p Vo l a t i l e Ma t t e r Pr o d u c e d i n t h e Sa m e Cr u c i b l e b e f o r e a n d a f t e r Po l i s h i n g.
P e r c en t, v o latile.
Coal No. Before. A fter. Difference.
10 17 ,0 18.1 1 .1
3 17 .0 18.1 1 .1
6 3 2 .6 3 3 .3 0 .7
T e m p e ra tu re °C. 845° 890° 4 5 °
1 J o u r. Soc. Chem. In d ., 23 (1904). J a n . 30, p. 50.
2 J o u r, fü r Gasbel. (1909), O ct. 9. p. 889.
T e m p e ra tu re m easu rem en ts. (°C.)
T im e in m in u tes. 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6 7 Before polishing, coal
N o. 1... 250 530 670 780 825 840 848 850 850 850 850 850 320 550 690 780 825 840 848 848 848 848 847 845 A fte r p o lish in g , coal
N o. 1... 240 590 750 840 880 890 890 890 890 890 890 890
Ta b l eX .—Vo l a t i l e Ma t t e r b y Di s t i l l a t i o n, P er cent.
v o latile
T e st T im e in m ois
N o. m in u tes. V acuum . tu re . R em ark s.
1 30 3 /4 -in . H g 1 8.3 R e to rt w eighed.
2 45 3 / 4 -in. H g 18.7 Coke weighed.
3 45 3 /4 -in . H g. 19.4 Coke weighed.
4 45 3 /4 -in H g 1 8 .2 Coke weighed.
5 = 40 4-in. H 2O 1 8 .8 Coke w eighed.
6 45 A tm o sp h eric pressure: 18.7 G ra d u a l h e at.
A verage, 18.7
7 7 A tm o sp h ere of CO2 18.5 f 30-grain p la tin u m cru-
8 7 A tm osphere of CO2 1 8.3 I d b le h e a t tre a tm e n t 9 7 A tm o sp h ere of CO2 1 8.6 I a s in official m e th o d .
A verage, 18.5 Official m e th o d , 19.3
In tests Nos. i to 6, inclusive, a sample of Poca
hontas coal was subjected to destructive distillation in an iron retort, m ade from a piece of i-in. gas pipe, capped at one end and tubulated a t the other. The retort was heated b y means of a train of Bunsen burners to a bright red heat, in a furnace of asbestos board. A 20-gram charge was used.
T ests Nos. 7 to 9, inclusive were made in a 30- gram platinum crucible 'w ith a tubulated cover;
carbon dioxide was kept passing through during the determ ination; the heat treatm ent was exactly the same as in the official method. B oth retort and cru
cible tests give results som ewhat lower than the official m ethod, although not m aterially.
SUM M ARY.
T h e results of these experim ents m ay be briefly sum m arized as follows:
Tw o laboratories are likely .to v a ry 2 per cent, in volatile m atter, both using the official method. The percentage of volatile m atter obtained from the same sample of coal varies w ith the tem perature and rate of heating. This is not sufficiently defined b y height of flame. Tem peratures ranging from 760° C. to 890° C. m ay be attained w ith a 20 cm. natural gas flame, when the gas pressure is varied from 1 to 13 inches of w ater; variations of 2 per cent, volatile m atter are thus produced. Difference in type and size of burner influence results from 0 .3 to 1 .5 per cent.
Polished crucibles become hotter and yield about 1 per cent, more volatile m atter than dull gray ones.
Laboratories using natural gas are apt to get re
sults on volatile m atter th at are considerably lower than those using coal gas, unless the following pre
cautions are observed:
(1) Gas should be supplied to the burner a t a pressure of not less than 10 inches of water.
3°8 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . July, 1910 (2) N atural gas burners adm itting an ample sup
p ly of air should_be used.
(3) G as and air should be regulated so th at a flame w ith a short, well-defined inner cone is produced.
(4) T h e crucibles should be supported on platinum triangles and kept in well-polished condition.
LABORATORY METHODS FOR ORGANIC NITROGEN AVAILABILITY.
B y C. H . Jo n e s. R eceived F e b ru a ry 17, 1910.
There is an extensive demand for nitrogen in a form suitable for plant food. This demand has been m ainly supplied in the past b y nitrate of soda, sulphate of ammonia, and the animal and vegetable ammoniates, including dried blood,- various tankages, fish scrap, bone meal and cottonseed-meal. These constitute a class which furnish nitrogen to the growing plant in a readily available form.
A s a supplem ent to these high-grade manures there has gradually come into use another group of nitrogen-containing materials including raw and treated leather, peat, tartar pomace, garbage tan k
age, mora meal, beet and gas-house refuse, and others.
Their nitrogen availability is supposed to be con
siderably less than obtains w ith the so-called stand
ard ammoniates, the nitrogen being so “ locked, u p ,”
“ fixed,” “ em balm ed” or “ in e rt” th at decomposi
tion in the soil is a long, slow process. M ostjfer- tilizer law's legislate against materials in this class, prohibiting their use unless statem ent of their pres
ence is made.
I t does not follow th at because a popular classifica- • tion puts a m aterial in the inert class, th at the m a
terial m ay not, b y suitable treatm ent, be so changed as to m erit a place in the readily available nitrogen group. T he personal equation must be eliminated and each material allowed to stand on its own merits as measured b y careful field and pot experiments.
In other words, the true availab ility of any source of nitrogen for plant food m ust be eventually deter
mined b y the growing plant.
I t happens, unfortunately, th at field and pot ex
periments cannot be conducted w ithout extensive equipm ent, th a t th ey are time-consuming, and th at the great variation in results under seemingly uni
form conditions, w ith different crops, soils, etc., necessitates repetition if anything like true availa
b ility averages are to be secured. This has led to the form ulation of short laboratory methods designed to differentiate between ammoniates of high and low crop producing power. A history of suggested m ethods is beyond the scope of this paper and would be out of place here.1
I wish to describe at this tim e first the alkaline
1 V t. S ta tio n , R ep ., 11, 1897, page 160.
perm anganate m ethod and second the pepsin diges
tion method as em ployed in the Verm ont Experim ent Station lab oratory and subm it results obtained by their use on fifty-one samples representing m an y so- called high- and low-grade anim al and vegetable am moniates now on the m arket.
The Alkaline Permanganate Method.— W eigh out an am ount of sample containing 0.045 gram of or
ganic nitrogen and transfer' to a 600 cc. distillation flask. A dd 100 cc. of alkaline perm anganate solution (16 gram s of pure potassium perm anganate and 150 grams sodium hydroxide dissolved in w ater and made to volum e of x liter), connect w ith a condenser to which a receiver containing standard acid has been attached, and digest below the boiling point for 30 minutes. Then boil until 85 cc. of the distillate are obtained. If the m aterial shows a tendency to ad
here to the sides of the flask, an occasional gentle rotation is necessary during distillation.
Pepsin Digestion Method.— W eigh out an amount of sample containing 0.025 gram of organic nitrogen.
W ith raw m aterials transfer to a suitable 150-200 cc. flask and add 100 cc. of a pepsin-hydrochloric acid solution. D igest for 24 hours in a w ater bath at a constant tem perature of 400 C., keeping flasks loosely corked. A t the end of the 2nd, 5th, 8th, and n t h hours, add 2 cc. of 10 per cent, hydrochloric acid solution. Shake well after each acid addition.
A fter the digestion filter the contents of the flask through single filters and wash until filtrate am ounts to 400 cc. D ry and determine nitrogen in the resi
due b y the K jeld ah l or Gunning method.
W ith com mercial fertilizers weigh the required am ount on a filter, wash w ith about 200 cc. water, and treat residue as already described.
The pepsin-hydrochloric acid solution is prepared b y dissolving 5 gram s of the Arm our & Co. soluble scale pepsin (1 : 3000 U . S. P.) in 1000 cc. of two- tenths per cent, hydrochloric acid.
In using this perm anganate method w ith commer
cial fertilizers it is necessary th at the nitrogen pres
ent as ammonia and as organic nitrogen be first de
termined. T h e am ount of material taken is based on the percentage of organic nitrogen present. N i
trates are unaffected b y the treatm ent, and a n y am monia orginally present in the sample is deducted from the result obtained before calculating the or
ganic availability. B oth nitrates and amm onia are given due credit under the total availab ility column.
In testing the availability of com mercial fertilizers, particularly when amm onia salts are present, it is rec
ommended th at the water-insoluble organic nitrogen be determined. A n am ount of m aterial equivalent to 0.045 gram of water-insoluble organic nitrogen is then w eighed onto a hardened filter, washed w ith about 200 cc. of w ater (small portions a t a tim e), the residue dried a t about 90° C. and transferred from the filter
