INDUSTRIAL AND ENGINEERING CHEMISTRY
January, 1927
109
volatilization has not been ascertained, however. I n the former case the method should be available for separation. As it stands it does not give quantitative results. Considered as criteria of the application of the various procedures to the quantitative estimation of the oxides these results in all but HC1 would often be satisfactory for small percentages. But in such cases the percentage losses would be likely t o be very much greater than here shown, for instance, sample 1 in Table I, which was from stock thoria, and sample 2, which was a residue from a separation from a relatively large quantity of tungsten with which the thoria had been incorporated in manufacture. I n such cases the residues are usually in the form of pseudomorphs, or rather phantoms, of the original wire greatly enlarged by the swelling accompanying oxidation, and therefore present an enormous surface to the action of the gas. As a large excess of the gas is always present,. it is reasonable to suppose that surface is the controlling factor in the speed of volatilization. I n thoria determinations, all of the oxides and the silica in any of the gases cause serious contamination of the thoria Table IV residue, for volatilization is never even approximately comLoss NOTOVER' GAS USBD plete. This means that the method for the determination of 2 per cent 10 per cent thoria in tungsten first described cannot safely be applied HC1 None None HC1 + 0% TiOz, ZrOr, Ah03 Taros to filaments of unknown composition without further operaClr Taros, AlzOs ZrOz CHC13 f Or TarOs Ti02 tions upon the residue. Although simple enough when plenty of material is a t hand, it cannot be used for residues of the The ceria results are inconclusive. Reduction was evi- size frequently met in actual practice. Owing to the high dent with HC1. The gain in weight in all the gases points degree of insolubility of nearly all of the oxides considered, to the formation of chloride. Whether this is incomplete even qualitative application of microchemical methods to without accompanying volatilization, or complete with some such residues is difficult.
method would indicate if certain refractory oxides other than T h o , were present in filaments of unknown composition, Ta205,Ti02, ZrOz, CeOz, and A1203,were studied to determine their behavior on heating in Clz, HCl, HC1 02, and CHCI, 02.The apparatus and procedure used for thoria were employed. As Pinagel's4 work has fully covered the behavior of silica in the presence of \NO3, it was not considered necessary t o repeat it. The fact that silica is wholly stable is important mainly because it may be an accidental impurity in filament tungsten. Unfortunately, the "fuming off" process with HF cannot be applied for its removal from other oxides in the case a t hand, because of the inconstancy in weight of platinum when heated in mixtures evolving even traces of CL. Transfer of the residues, owing to their minuteness and physical character, is impracticable. The behavior of the oxides studied is given in Table 111. If the total time of heating is not more than 3 hours, the loss shown in Table IV results.
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Conversion of Fibroin,' Chitin, Casein, and Similar Substances into the Ropy-'Plastic State and Colloidal Solution' By P. P. von Weimarn E(oGYoSHIKENSHO,
S EARLY as 1912 the writer3 established the fact that aqueous solutions of any readily soluble salt capable of strong hydration possess the ability to convert cellulose into the plastic state and to produce the colloidal dispersion of cellulose. The concentration of the solut'ion, the temperature a t which the dispersion of cellulose proceeds, and the time necessary to complete the dispersion vary with the salt taken, its solubility, and its degree of hydration. If by the ability of salts to produce dispersion (designated by the symbol D ) we underst'and the magnitudes directly dependent on the average rates of dispersion of the same kind of cellulose (other conditions being equal), then the following series of inequalities4 lvould be both theoretically and experimentally established for certain lithium and calcium salts :
A
DLicss
>
DLiI
D c ~ ( c N s )>~ Dcalz
> >
DL~B~
D c ~ B ~ ~
Japanese Patent Application; patentee, Imperi'il Industrial Research Institute of Osaka; inventor, €'. P . von Weimarn; date of invention, December, 1926. Patent application cause of several months' delay in publication of results obtained by writer. 2 Received July 27, 1926. 8 R u s s i a n Chem. SOL, 44, 772 (1912); Kolloid-Z., 11, 41 (1912); English translation in Repls. I m p . I n d . Research Inst. Osaka, J a p a n , 4, No. 7, 17 (1923). 4 von Weimarn, J . Ckem. Educotiun, 3, 378 (1926). 1
D A I N l , OSAK.4,
JAPAS
These six salts are examples of salts with high dispersion abilities. I n 1913 the author5 announced that in theory aqueous salt solutions are able of dispersing not only cellulose, but also other dispersoids capable of hydrolysis into solubIe products. I n other words, such organic colloids as fibroin (the chief constituent of natural silk), chitin (containing nitrogenous polysaccharose-i. e., the nearest analog t o cellulose, the chief constituent of the shells of cuttlefish (sepia), crayfish, crabs, lobsters, beetles, etc.), and similar colloids, are also convertible by means of concentrated aqueous salt solutions into the ropy-plastic state and into colloidal solutions, Fibroin
This theory was not proved experimentally by the author until the middle of December, 1925, with fibroin, and, in collaboration with Utzino,6 a t the beginning of 1926 (February-March) with chitin, casein, fibrin, and keratin. Fibroin (silk wadding being used for experimentation) proved to possess a considerably higher colloidal dispersa5 Ann. SI. Petnsburg Mining Inst., 4, 151 (1913); German translation, Kolloid-Z., 29, 198 (1921) ; English translation, Refits. I m p . I n d . Research Inst. Osaka, J a p a n , 4, No.7, 23 (1923). I n the laboratory of physical chemistry, Imperial University of Kioto, S. Utzino is now submitting to a special study the hydrolytic action of concentrated aqueous solutions of neutral salts upon the substances mentioned above.
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I;VDC'STRIAL AfiD ENGl 'NEERING CHEMISTRY
110
bility in aqueous salt solutions than cellulose. For instance, LiCNS solutions produce colloidal dispersion of silk wadding at room temperature (25O C.) and, of special practical importance, 10 grams of silk wadding may be dissolved in 7 to 10 minutes in 100 cc. of neutral aqueous solutions of such common and cheap salts a8 CaCL or Ca(NO& at t,heir boiling temperature (115" C.). The preparation of 30 per cent colloidal solutions of silk i n the solutions of these salts is quite pos&le.
Vol. 19, No. 1
Casein
With casein i t was observed (investigations were limited to heating casein with CaC& solutions under ordinary pressure) that CaCll solutions, although converting the casein into the ropy-plastic state, fail to produce colloidal dispersion or dissolve it very little; Ca(CNS)s, CaI,, and CaRr, solutions, however, produce a marked colloidal dispersion of casein. Casein is most easily dispersed in LiCNS solutions. Even in cold solutions (25' C.) it may go spontaneously into the colloidal solution. Fibrin and Keratin
The dispersion of fibrin and keratin in salt solutions is carried out with more difficulty than the dispersion of cellulose or chitin. However, extremely soluble salts-e. g., LiCNS and Ca(CNS)*-in strongly concentrated solutions disperse these substances to a marked degree. For instance, keratin (in the form of pure white woolen yarn) in extremely concentrat,ed LiCNS solutions (between li0" and 200" C . ) , after swelling, rapidly assumes a translucent, jellied plastic state, and on further heat.ing passes over into the colloidal solution. Rate of Dispersion
FiBurr 1- Filament Farmed by Treating Calcium Nifrate Solution of Fibroin w i t h Ethyl Alcohol
Fibroin may be separated from these colloidal solutiow in a perfect ropy-plastic state by means of various deliy&sting and coagulating substances and also by ultra-liltrat.ion and centrifugation. A filiform coagulum may he obtained with ethyl alcohol. To a 10 per cent colloidal solution of fibroin in an aqueous solution of calcium nitrate, cooled from 115' C . to 50-25O C., ethyl alcohol at ordinary b p e r a t u r e (25-20' C.) is added, the contents being constantly stirred with a glass rod. A thread-like precipitate of fibroin is formed, which will wind round the glass rod like a reel. The ropy-plasticity of this precipitate permits it to be greatly extended, as is secn in Figure 1. Figure 2 shows a photomicrograph of a thin thread of such a precipitate. The thread represents tJie combination of many almost parallel filaments. The dispersion abilities of salts for fibroin are connected by a series of inequalitics similar to that which exists for cellulose: B
> >
Ijc.(cas)*
Ikii
I1c.n
> >
D ~ i i i ~> Druc D c . m > I)C,CI~
Chitin 111 collaburtition with Utziiio, the writer succeeded in establishing the fact that chitin (both that prepared from the intornal sliell of sepia, also that from a Jaiianese kind of lobster "kuruma-ehi") is also convertible into the plastic state as well as into the state of colloidal solution by ITI~:IIIS of aqlieons salt solutions. The following inequalities, similar to those for cellulose, exist for chitin: 1)Lich.s > U C ~ ( C N> B )Dc,rr ~ > 1)c.m > Dcsciz In the solutions of calcium chloride. chitin disverses witli difficulty. The mooerties of colloidal solutions of chitin in salt . . solutions approach in some respects those of cellulose; but the gelatinous precipitates and jellies obtained by the addition of ethyl alcohol to chitin-e. g., from LiCKS solution-are perfectly translucent, whereas they 3,re almost opaque when cellulose solutions H ~ Ot,lms preeipitabed.
The rate of dispersion (colloidal dissolution) of all these substances is dependent not only on the nature of the salt used and the concentration and demperature of its solution, but also to a considerable extent upon the life history, age, the previous treatment, and the degree of purity of the DreDarations taken for emenmentation. The followine
ebi,'. c o n s i d e r a b l y Fieure 2-Phofomicrofiraph of mlamenf larger a n d having a srecipirate. x 200 much thicker and more compact shell than the "kumma-ehi" (designated as I). These gave the followinginequalities for D: I j , ~ t i ~ n
>
Desi,inx
>
DChitii)i
Chitin S disperses most easily and rapidly into the colloidal solution, while chitin I is dispersed slowly and with much difficulty. The writer's experimenLs bring him to the conclusion that the same range of inequalities holds for all the substances mentioned above, thus: 1jLiCh.S
>
>
~ ) G ~ ( C S S ) ~
IjLd
>
DLm?
>
>
Dc.am
>
U K ~ C S>S DN*T Dcnra
DLiCi
Dcncir
herefo fore, it would be possible to dissolve colloidally cither cellulose together with fibroin, or cellulose, chitin, and fibroin simultaneously, in aqueous sohitions of some extremely soluble salt, such as XaI, LiBr, Li(CNS1), or
CU(CSS)% From these colloidal solutions complex plastic masses may be obtained, such as: x.cclloiose 3- y.fibroin; n.celluiose y.chitin + z.fibroin, etc. Hence i t is the writer's conviction that the scientific and technical study of the properties of such complex plastic niasses and their resulting filaments is of great interest. not only from the dispersoidological standpoint hut because it opens up a wide horizon to the artificial fiber industry.
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