Determ ination of p H of am m oniafcal] latex.
J. McGav a ck and J. S. Hu m b old (Ind. Eng. Chem.
[Anal.], 1931, 3, 94—97).—Most of the indicators avail
able for p h determinations in alkaline liquids are un
satisfactory on account of their small colour change ; the presence of proteins also frequently causes large errors. The glass electrode is very satisfactory with latex ; up to 9 • 5 the variation is negligible, and a reasonable degree of accuracy is obtained even at p s 11-0; above this value, however, it is necessary to calibrate each electrode, using, e.g., Sorensen’s glycine- sodium chloride-sodium hydroxide standards. (Cf.
Hughes, A., 1928, 370.) D. F. Twiss.
Determ ination of alkalinity of reclaim ed rubber.
H. F. Pa l m e r and G. W. Mil l e r (Ind. Eng. Chem.
[Anal.], 1931, 3, 45—48 ; cf. Shepard, Palmer, and Miller, B., 1928, 238).—The reclaim, sheeted to a thick
ness of approx. 0-001 in. and torn into pieces about 1 in. in diam., is heated under reflux on a hot-plate at 110° with a neutral mixture of benzene (60 c.c.), alcohol (40 c.c.), and water (100 c.c.) for 2 hrs. More water (500 c.c.) is then added and the benzene removed by evaporation. The solution is decanted and the solid then washed thrice with 75 c.c. of boiling distilled water.
Hydrochloric acid (0- 1A7) is added to render the com
bined washings and original extract distinctly acid, followed by approx. 5 c.c. each of 3% potassium iodate solution and of iV-potassium iodide ; after 3 min. the same volume of 0-liV-thiosulphate is then added as of lY-hydrochloric acid earlier, and after 15 min. the mixture is titrated with 0 -lAr-iodine and starch. This indirect method of titration avoids the difficulty offered by the colour of the extract. The procedure gives much more accurate results than those obtainable previously
(loc. cit.). D. F. Twiss.
M anganese and iron contents of various typ es of rubber and fillers and th eir im portance for the ageing behaviour of rubber. F,. Kir c h h o e (Kaut- schuk, 1931, 7, 26—33).—Washed plantation Hevea rubber normally contains manganese up to about 0-0001% Mn, bu t wild rubbers may contain up to 0-002% ; raw Tjipetir gutta also shows a distinct manganese content. Sticky low-grade rubbers always have a relatively high content of manganese and of iron.
The contents of these metals are not related in any very definite way to the percentage of ash, and it is possible th a t the manganese is, in part a t least, in organic com
bination. This possibility is supported by the fact th a t
the viscosity of sticky low-grade rubbers varies inversely as the proportion of manganese in the soluble portion.
In a sample of Peruvian ball rubber containing 0-007%
Mn and also iron, the condition was one of fluidity rather than stickiness. The degradation is attributable to an oxidation-depolymerisation process in which the man
ganese acts as c a ta ly st; the change can eventually proceed further to the formation of a hard resinous surface layer. Some mineral fillers such as ochres, umbers, whiting, and mineral blacks also contain dis
tinct proportions of manganese and impair the ageing qualities of vulcanised mixtures, which consequently show a rapid increase in the acetone-soluble fraction.
The presence of 0-05% Mn in a vulcanisate is regarded as dangerous, particularly if the mixing contains much
iron oxide. D . F . Twiss.
Organic colours in the rubber ind u stry. F.
Jacobs (Kautschuk, 1931, 7, 22—26).—A large number of organic rubber colours of British, American, German, and French manufacture are brought under review as to their behaviour during vulcanisation (in open steam) in rubber mixings containing various accelerators and with and without the additional presence of tube reclaim. The presence of reclaim is generally detri
mental to the colour and necessitates the use of an increased proportion of white filler and of pigment.
The identity of certain colours sold commercially under different names is indicated. D . F. Twiss.
Pa t e n t s.
Coagulation of [rubber] latex. Go o d y e a r Tir e
& Ru b b e r Co., Assees. of A. J . Gr a c ia (B.P. 342,485, 2.1.30. U.S., 8.4.29).—Latex is coagulated by the addi
tion of an amine of the formula CH2R -N R 'R ", where R is an aromatic or aliphatic hydrocarbon group and R ' and R " may be hydrocarbon groups or hydrogen.
Examples are ethylamine, diethylamine, and their homo- logues; a satisfactory proportion is 5 c.c. per 50 c.c.
of latex. D. F. Twiss.
Production of aqueous d ispersions of organic substances [for addition to rubber latex], D u n l o p R u b b e r Co., L t d . , and A n o d e R u b b e r Co., L t d . , Assees.
of A. S z e g v a r i (B.P. 342,194, 18.3.30. U.S., 20.4.29).—
“ Rubber oil,” prepared by the destructive distillation of raw or vulcanised rubber, is used to dissolve organic materials such as accelerators or anti-oxidants, e.g., of the aldehyde-amine type, asphaltum, or vaseline. The solutions are then dispersed in water by shaking, pre
ferably with the addition of emulsifying agents.
D. F. Twiss.
T hickening and stab ilisin g of [rubber] latex. M.
C. Te a g u e, Assr. to Am e r. Ru b b e r Co. (U.S.P. 1,772,647, 12.8.30. Appl.. 7.12.27).—Latex of not less than 60%
concentration, compounded if desired, is thickened and stabilised by the addition of a t least 0-5% of saponin (rubber 100). The product is suitable for such purposes as dipping, spreading, extruding. D. F. Twiss.
(a) T reatm ent, (b) preservation, of [rubber] latex.
J . McGa v a c k, Assr. to Na u g a t u c k Ch e m. Co. (U.S.P.
1,772,752—3, 12.8.30. Appl., [a] 27.3.29, [b] 16.4.29).—
(a) In the concentrating of latex by creaming, economy may be effected in the amount of creaming agent (e.g.,
Cl. X IV .— In d i a- Ru b b e r ; Gu t t a- Pe k c i i a. B r itis h C h e m ic a l A b s t r a c t s —B .
407
ammonium alginate) consumed, and an increased pro
portion of serum solids may be ensured in the cream, by introducing into the uncreamed latex a quantity of the serum obtained in a previous creaming operation.
(b) The soluble salts of selenious and tellurous acids are effective anti-coagulants for rubber la te x : 0-1%
(on the latex) will preserve latex for several months.
D. F. Twiss.
Vulcanisation of rubber. B. S. Ga r v e y, Assr. to B. F. Go o d r ic h Co. (U.S.P. 1,774,322, 26.8.30. Appl., 19.4.29).—Rubber containing sufficient rubber for com
plete vulcanisation is mixed with a metallic trithio- carbonate, e.g., barium trithiocarbonate, and a sub
stance such as a secondary aliphatic amine or a reactive non-volatile derivative of such a base, e.g., pipeiidine- formaldehyde. Such mixtures show substantially no tendency to vulcanisation below 100°, b u t at higher temperatures decomposition of the trithiocarbonate occurs with liberation of carbon disulphide ; this then combines with the secondary amine with formation of a very active, accelerator of vulcanisation.
D. F. Twiss.
Vulcanisation of rubber. W. Sc o t t, Assr. to Ru b b e r Se r v ic e La b s. Co. (U .S .P . 1,773,379, 19.8.30.
Appl., 10.5.29).—The reaction product obtained from molecular proportions of an aliphatic aldehyde, such as acetaldehyde or butaldehyde, and a hydroxyaryl com
pound, such as phenol or (3-naphthol, in the presence of a small proportion of condensing agent, e.g., hydrochloric acid, is further heated a t 170—200° with an atomic proportion of sulphur and a catalyst, e.g., 0-2% of iodine. The final product is of value as an anti
oxidant in vulcanised rubber. D. F. Twiss.
T reatm ent of rubber. Na u g a tu c k Ciihm. Co., Assees. of L. H. Ho w l a n d (B.P. 342,634, 6.6.30. U.S., 22.6.29).—The products obtained by the interaction of a carboxylic acid, e.g., acetic, stearic, or salicylic acid, with a diarylamine, e.g., diphenylamine or phenylnaphthyl- amine, in the presence of a dehydrating agent are of value for retarding the deterioration of rubber. They are
W GSO-substituted acridines of the general formula
RC^~“ ^ N , where R ' and R " are o-arylenc radicals
X l V r /
and R may be any substituted organic radical including, if desired, an additional weso-substituted acridine.
D. F. Twiss.
Treatm ent of rubber. Na u g a t u c k Ch e m. Co., Assees. of S. M. Ca d w e l l and S. I. St r ic k h o u s e r
(B.P. 342,502, 18.1.30. U.S., 19.1.29).—Deterioration of rubber during vulcanisation and subsequently is retarded, without leading to discoloration, by incor
porating a mixture of an organic base and a naphthol, particularly a monohydric naphthol. The naphthol neutralises the accelerating effect of the organic base and at the same time itself acquires anti-oxidant properties, thereby augmenting the anti-oxidant effect of the base. Suitable bases are, e.g., open-chain or other polyalkylenepolyamines, ^'-diam inodiphenylm ethane, and their aldehyde or nitroso-derivatives.
D. F. Twiss.
Dispersed p lastic m a sses. K.D.P., Li d. (B.P.
342,469, 20.12.29. Ger., 22.12.28).—By the addition of
thixotropic colloids such as bentonite, or of lithium sulphate or other suitable electrolytes, the natural or added colloids in colloidal dispersions of plastic materials such as rubber are rendered thixotropic. Liquids such as oil may also be added to increase the elasticity of the thixotropic mixture. The ability of such mixtures to undergo reversible conversion into a fluid condition by agitation renders them advantageous for manufacturing operations such as dipping, spreading, etc.
D. F. Twiss.
M anufacture of rubber-like m a sse s and articles therefrom . A. Ca r p m a e l. From I. G. Fa b b e n in d. A.-G. (B.P. 342,314, 30.8.29. Addn. to B.P. 339,255;
B., 1931, 264).—In the process of the prior patent, the styrene can be replaced by other defines such as homo- logues of styrene, benzene hydrocarbons containing two or more substituent vinyl groups, or homologues of these hydrocarbons. D. F. Twiss.
P roduction of variated surface effects on rubber articles. J . B. Cr o c k e t t, Assr. to Ca m b r id g e Ru b b e r
Co. (U.S.P. 1,773,724, 26.8.30. Appl., 14.5.29).—A former of the desired shape is coated, by spreading, spraying, or similar procedure, with a layer of vulcanis- able or vulcanised compounded latex containing a high proportion of mineral filler. On drying, the rubber layer cracks or checks in an irregular manner over its entire surface. After drying, compounded latex of contrasting colour and containing a much lower propor
tion of filler is applied to the coated former until the article has been built up to the desired thickness. The article is then dried and/or vulcanised preferably before stripping. The character of the irregular pattern may be modified by varying the proportion of filler and the drying tem perature of the first coating. D. F. Twiss.
Com posite product [rubber bonded to m etal].
H. Gr a y, Assr. to B. F. Go o d r ic h Co. (U.S.P. 1,774,324, 26.8.30. Appl., 22.4.27).—A vegetable oil (tung, linseed, castor, or rosin oil) is treated with one or more of a class of compounds comprising strong inorganic, non-oxidising acids and compounds capable of undergoing thermal or hydrolytic dissociation to form such acids, e.g., sulphuric acid, aluminium chloride, phosphorus oxychloride, sulphur chloride, benzotrichloridc, trichloroacetic acid.
The products form strong bonds between solid materials, particularly metals and rubber. D. F. Twiss.
Production of com binations of rubber and paper.
R. P. Ro se and H. E. Cu d e, Assrs. to Ge n. Ru b b e r Co.
(U.S.P. 1,773,201, 19.8.30. Appl., 18.12.26).—During the beating of papermaking fibre, a protective colloid, such as glue or a soluble starch ester, is added. Rubber latex is then introduced, preferably after rendering the fibre mixture alkaline, and the deposition of the rubber on the fibre is then effected, e.g., by the addition of a coagulant. When glue or other protein is used as protective colloid it is advantageous to effect precipi
tation of the protein as well as of the rubber. This procedure facilitates the manufacturing operations and gives rubber particles of much smaller size th an those in ordinary latex paper. D. F. Twiss.
Im pregnating com position .—See X III.
66 2
B r i t i s h C h e m ic a l A b s t r a c t s —B .
408 Cl. X V . — Le a t h e r ; Gl u e.
XV.—LEATHER; GLUE.
D efects in raw hides and th eir resu ltin g effects on the finished leath er. F. St a t h e r (J. Soc. Leather Trades’ Chem., 1931, 15, 12—21).—In addition to mechanical damage and damage arising from parasitic attack and pathological causes, many defects arise through the action of micro-organisms, which can cause salt stains, red coloration, violet stains, low grain, decomposed grain, development of arteries, and the marbling of the grain. Stains or grain damage is produced b y alum, lime, iron, copper, and chromium salts, also by the crystallisation of salts in the skins.
Stains are produced by dung and urine. Damage is caused if the hides are allowed to heat, sweat, or dry too quickly. These various causes are discussed in detail and in some cases the appearance of or effect on the finished leather is described. D. Wo o d r o f f e.
Origin of am m onia found in lim e liquors [from treatm ent of hides or sk in s]. R . H. Ma r r io t t (J . Soc. Leather Trades’ Chem., 1931, 15, 25—30).—By treat
ment of hair and collagen, respectively, with lime liquor, it was shown th a t relatively large amounts of ammonia were formed from collagen, and after 8 days the ratio of non-amino- to amino-nitrogen was larger than in any commercial liquor which had been tested. The ratio for the hair was not so large. Analysis of the lime liquors and of the protein m atter showed th at, with collagen, all the ammonia in the lime liquor was derived from the amino-groupings of the protein. The am monia derived from the hair was greater than could have been derived from the amino-groupings alone, and it is concluded th a t the excess must have resulted from the decomposition of cystine groups. The ammonia in lime liquors is derived partly from the decomposition of protein amino-groups and partly from the alkaline hydro
lysis of the cystine groups in the hair and of the albumins and globulins in the interfibrillary proteins.
D. Wo o d r o f f e. Im portance of the p H of pelt in vegetable tanning.
G. P e a c e (J. Soc. Leather Trades’ Chem., 1931, 15, 22—24).—Hide powder plumping curves are not strictly comparable with the plumping of hides in actual tanning.
In most tanneries sole leather is tanned in liquors of too low a p a value, resulting in dark cracky grain unless extra finishing processes are applied. The addition of acid to tan liquors to reduce the p H to below 3 is unnecessary, since excellent substance, weight, and solidity are obtained a t p& values above 3.
The f n of the ta n liquors regulates itself if the tannage is commenced in weak liquors, and if the p u of the hide fibres is a t the best value when tanning commences.
The hides should be delimed completely and then their adjusted to the required value, which will depend on the kind of leather to be made and the materials in use. The most useful values are p s 3-5—
5-0. D. Wo o d k o f f e.
Quick tanning. M. Be r g m a n s, W. Munz, and L.
Se u g s b e r g e r (J. Soc. Leather Trades’ Chem., 1931, 15, 67—72).—The speed of penetration of solutions of Neradol ND, a- and p-naphthalenesulphonic acids is 10—20 times as great as th a t of water. Although their solutions have pn 1-02—1-88, the swelling pro
duced by them on hide powder is less th an th a t in wrater. From figures obtained by the Dresden penetra
tion apparatus, it has been shown th a t the capillaries of the pelt are enlarged by treatm ent of the latter with the above solutions. The sum of the water of swelling and of absorption is reduced, so th a t a reduction of swelling m ust have taken place. The pelt is rendered thicker, less compressible, and more resistant by the above solutions. By their use the rate of tanning action is increased. D. Wo o d r o f f e.
D eterm ination and control of the buffer index of tan liquors. (Miss) W . B . Pl e a s s (J. Soc. Leather Trades’ Chem., 1931,15, 73—78).-—The “ bufier index ” of a tan liquor (c.c. of jY-hydrochloric acid or IV-sodium hydroxide required to alter the p n of 100 c.c. of the liquor a t d 1-020 by 1 unit) may be ascertained by diluting the liquor to d 1-020, measuring its value, and adding to 100 c.c. of the diluted liquor known volumes of iV-sodium hydroxide (if the pn is less than 3) or AMiydrochloric acid (if greater than 3) until the p H value has been altered by 2 units, the p H of the liquor being determined after each addition of acid or alkali. The pn values are plotted against the volumes of alkali or acid added and the buffer index is deduced from the slope of the curve. For liquors of d <C 1-020, the titration curve is obtained a t the original concentra
tion of the liquor and a correction factor to the buffer index, as computed a t th a t concentration, is applied.
This index is a measure of the mellowness of a tan liquor, and varies with the tanning materials used (bottom suspender liquor, average value 4-5 : top, 3-0).
Liquors of high buffer index usually give poor plumping, bu t a softer, fuller leather. Unevenness in the weave of the leather fibres is produced if the buffer index and p H value vary much from the middle suspender liquor to the lower handlers. The buffer index is increased as the tan liquor passes down the yard or by additions of lactic acid, but is diminished by sulphuric acid. The pH is slightly lowered by additions of these acids.
D. Wo o d r o f f e. Fat-liquoring of chrom ef-tanned] leather.
Effect of hydrogen-ion concentrations on oil ad
sorption. E. R. Th e isand F. S. Hu n t(Ind. Eng. Chem., 1931, 23, 50—53).—Characteristic fat-adsorption curves for various oils were obtained by fat-liquoring chrome leather over the range p a 1—12. Maximum absorption of oil was shown a t p u 4-0. Greater dispersion of the oil and speedier absorption were obtained by the addi
tion of “ trietlianolamine ” to the fat-liquor ; less oil was absorbed, but the leather was more pliable. By varying the pu of the fat-liquor, the adsorption curves exhibited maxima in all cases ; thus for sulphonated neatsfoot oil this occurred a t 10, for sulphonated cod oil over the range 1—5, and for moellon a t p a 6—8.
Less oil was absorbed from a sulphonated n e a ts fo o t oil-egg yolk fat-liquor than from a sulphonated neats
foot oil fat-liquor a t p n 1—4 '5 and ]>6-75, but more over the range pH 4-5—6-75 (cf. Merrill, B., 1928, 580). The contraction of the skin by fat-liquoring was rapid during the first hour and attained e q u ilib riu m
in 90 min. D. Wo o d r o f f e.
Acidity of leather. H . G. Be n n e t t(J. Soc. L e a th e r Trades’ Chem., 1931, 15, 31—38).—A modification
B r itis h C h e m ic a l A b s t r a c t s — B .
C l. X V I.—Ag r i c u l t u r e. 4 0 9
of Thompson and Atkin’s method of determining acidity (B., 1929, 865) is proposed. The fat-extracted leather is exposed to the air for 48 hrs. and its moisture content (W % ) determined. Two portions of leather (101/17 g. and 10-1 jW g.) are left in contact with 0-lA r-potassium chloride for 24 hrs., and, after filtration the p n values of the filtrates, pnn and j>n3, respectively, are determined by means of the comparator.
The p H (or “ acid figure ” ) of the original leather is then expressed by 3^ho—2pn3 and the equation of the graph showing the relation between the pH of the leather and dilution (D) is : p K = (fu ^ —lhi2)D-\-(3pn2—
2^i[3). The average p a for leathers was 3-5. In one case it was below 2-5, the minimum suggested by Atkin and Thompson. High p u values were usually associated with a steep slope to the curve, and low values with leathers of low ash value. The pa appeared to be buffered by the presence of mineral m atter in the
leather. D. Wo o d r o f f e.
D ensity data on leather. I. D. Cl a r k e (Ind. Eng.
Chem., 1931, 23, 62—67).—The actual density was determined as follows : the weighed leather was pu t into a known volume of kerosene in a graduated tube or pyknometer and suction was applied interm ittently for 2—3 hrs. until all the air had been removed. The increase in the volume occupied by the leather and kerosene was the actual volume of the leather. The apparent volume was determined by removing the leather from the tube, wiping off surface kerosene, and noting the increase in volume caused by returning the leather to the tube. The percentage of voids was obtained by expressing the difference between the apparent and actual volumes as a percentage of the apparent volume.
Possible sources of error are indicated. Temperature control is necessary. Actual densities of different leathers are nearly constant a t 1 • 327—1 • 433. Determina
tions of the apparent densities and percentage voids of leathers yielded the following re su lts: vegetable-tanned sole leather 0-95—1-05, 25—30% ; vegetable- tanned upper and dressing leathers 0-80—0-90, 30—
40% ; unwaxed chrome-tanned leather 0 -.60—0 • 70, 50—60%. The percentage of voids was diminished by filling the leather with grease, tannin, etc. or by mechani
cal means, e.g., rolling. I t was affected by the nature of both the skin and the tannage. Fewer voids are found in vegetable than in chrome tannages.
D. Wo o d r o f f e. Furs.—See VI. T annery effluents.—See X X III.
Pa t e n t s. Dryer.—See I.
XVI.—AGRICULTURE.
Presence of uronic acids in so ils. |E . C. Sh o r e y
and J. B. Ma r t in(J. Amer. Chem. Soc., 1930,52, 4907—
4915).—Application of the modification of Lefevre and Tollens’ method for determining uronic acids described bv Dickson and co-workers (A., 1930, 453) to 11 soils indicates the presence of 0-308—7-938% of uronic acids; the soils are first heated with 1% hydrochloric acid to decompose inorganic carbonates (the possibility of some of the carbon dioxide evolved being formed from uronic acids is noted as being probable). The presence
of uronic acids (or polyuronides) in two of the soils is confirmed by extraction with 2% sodium hydroxide solution; the extracts are acidified with acetic acid, then neutralised with barium carbonate, evaporated to syrups, and these added to 95% alcohol, whereby
of uronic acids (or polyuronides) in two of the soils is confirmed by extraction with 2% sodium hydroxide solution; the extracts are acidified with acetic acid, then neutralised with barium carbonate, evaporated to syrups, and these added to 95% alcohol, whereby