OROANIC CHEMISTRY. BY

ALPRED N. COOK AND ARTHUR L. HAINES. Proc. Iowa Acad. Sa.., 9, 86-90 (Igor).-The experiments conducted by the authors indicate that methyl, ethyl, butyl and amyl alcohols can be completely dehydrated by the action of calcium carbide. The progress of the dehydration was ascertained by determining the specific gravity of the alcohol at I 5.5' before and after the treat- inent with carbide.

p-Oxy-m-Methylacetophenone and Some of Its Derivatives. BY J. G. GOODWIN. Proc. Iowa Acad. Sci., 9, 113-119 (IQOI). -In the preparation of P-hydroxy-m-methylacetophenone by the method of Nencki and Stoeber, the use of carbon tetrachloride as solvent instead of carbon bisulphide considerably increases the yield. The melting-point of the pure substance is 106", and i t gives no color reactions with ferric chloride or with caustic soda. I ts solubility in water at 2 2 " is 0.035 per cent.; at 70°, 2.56 per cent. I ts methyl ether melts to a colorless oil at 2 j 0 , while the ethyl ether is a white solid, m . p. 34.5".

Certain Derivatives of Trichlorethylidene-Di-p-Nitrophen- amine. BY ALVIN S. WHEELER, AND M. R. GLENN. Jour. Elisha Mitchell Sci. SOC., 19, part 2 , 63-66 (1903). Trichlorethyl- idene-di-p-nitrophenaniine is obtaiued by the condensation of chloral with #-nitraniline, and is a yellow, insoluble, crystalline powder, melting with decomposition at 216'. I t is attacked by zinc dust aud acetic acid, but the nature of the product has not as yet been fully worked out. Alcoholic potash changes the tri- c h lore t h y 1 idene body to dichlorhydroxylet~y~~dene-di-~-nitrop~en- amine, CCl,(OH)CH(NHC,H,NO,),; yellow prisms (from alco- hol), turning brown in the air, m. p. 177'-178' (uncorr.); solu- ble i n boiling water, in methyl or ethyl alcohols, ether, hot chlo- roform, hot benzene, or cold acetone, soluble in 75 parts boiling alcohol, but only difficultly soluble in cold absolute alcohol. If sodium methylate be used instead of alcoholic potash, the product is dic~lo,-methoxyethyZidene-di-p-nifrophetiamine, light-yellow, rec- tangular plates, in. p . 176"-177'. By the action of a glacial acetic solution of bromine upon the trichlorethylidene compound a bro- mine derinative, melting at 202 '-203 ", is obtained, the character of which has not yet been determined.

On the Electrolytic Preparation of Iodoform from Acetone. By HOWE ABBOTT. J. Phys. Ckem., 7, 84-91 (1go3).-After a systematic study of the subject, the author finds that the most favorable conditions for the preparation of iodoform from acetone by electrolysis are as follows : ( I ) A current density of not more than 1.35 amperes per square decimeter ; (2) a temperature of

Calcium Carbide as a Dehydrating Agent for Alcohols.

M. T. BOGERT.

M. T. BOGERT.

M. T. BOGERT.

560

75’ C. ; ( 3 ) an anode solution containing 6 grains sodium carbon- ate, I O grams KI , IOO cc. water, and 5 . j cc. acetone added at the rate of 0.5 cc. every ten minutes during the electrolysis. The yield of iodoform is much larger than that secured by Elbs and Herz, who used alcohol instead of acetone.

The Action of Alkaline Sulphides upon p-Nitrobenzylaniline. BY FREDERICK J. ALWAY AND ARTHUR B. WALKER. Am. Chem . 3, , 30, I 05- I I 0. --Prepam tioii of#- Nif robeii zyla 12 iline . --If I molecule p-nitrobenzylchloride and 2 molecules aniline, in con- centrated alcoholic solutioii, be heated together on the nater- bath for two to three minutes, the yield of p-nitrobenzylaniline is 92 per cent. of the theory. An equally good yield may be secured by boiling together for a few minutes I molecule of the fi-nitro- benzylchloride with 4-6 molecules of aniline. Artioiz of Caustic AlkaZies upon p-Nitrobenzylaniliiie.-By the action of caustic alka- lies upon a hot alcoholic solution of p-nitrobenzylaniline, p-azoxy- benzylidenaniline is produced, the yield reaching a maximum when I molecule of the caustic is used to 4 molecules of the nitro body. Actio72 of Alkaline Sulf hides @on p-Nitrobe?zzylaiziline.- Alkaline sulphides convert an alcoholic solution of p-nitrobenzyl- aniline into P-azoxy- and p-amino-benzylideiianiline. The best yield of the azoxy body is obtained when I niolecule of the sul- phide acts upon eight of the nitro compound. ,is the proportion of sulphide is increased the yield of the azoxy compound decreases and that of the amino compound increases. M. T . BOGERT.

The Relations Existing between the Physical Properties and the Molecular Weights of p- and vi-Nitrosobenzaldehyde. BY FREDERICK J . ALWAY AND WALTER D. BONNER. .4nz. Chem. 1. 30, I I 1-1 I 5.-Nearly all nitroso compounds possess the property of forming colorless solids, while in solution or in the liquid state they exhibit a strong green or blue color, the color- less form being due to a dimolecular condition, while the mono- molecular state is present in the colored solutions and melts. Both m- and p-nitrosobenzaldehyde are green i n the liquid state or i n solution ; the meta compound forms white crystals, while the para forms yellow ones. The para body is, therefore, ex- ceptional in that it is not colorless in the solid state, and the molecular weight determinations furnish no explanation of the cause of this anomaly., In boiling lienzene and in freezing acetic acid, both m- and p-nitrosobenzaldehyde shorn normal niolecular weight ; i n freezing benzGne, the para body is monomolecular, the meta partly dimolecular, the change in condition of the latter being accompanied by a change in the intensity of the green color of the solution. A change in the color of the para solution, on the other hand, is accompanied by a separation of yellow crystals. M. T. HOGEK’I’.

Review of Anierica?i Chemical Research.

hl. T. BOGERT.

Organic Chemistry. 561

Certain Substitution Derivatives of Ethyl Anilinornalonate. BY RICHARD SYDNEY CURTISS. A m . Chem. J., 30, 133-144.- The substance previously reported as the product of the action of nitrous acid upon ethyl anilinomalonate is believed to possess one or :he other of the following structures :

C,H,N\ /COOC,H,

I.

C,H,N( NO)-CH( COOC,H,),. ' /c\cooc,*, 11. HO-N

As this substance breaks up very readily, the nitroso deriva- tives of the corresponding 0-, m- and p-toluidinomalonates were investigated in the hope of finding more stable substances. The ethyl 0- , m- and p-toluidinomalonates were prepared from ethyl brommalonate and the required toluidines. They are weak bases, their salts with strong acids being dissociated by water. Treated with nitrous acid, they yield thick, amber-colored oils, which give yellow solutions or stable, yellow, crystalline salts wibh caustic alkalies, show the Liebermann nitrosamine reaction, and are slowly colored deep red by ferric chloride. EXPERIMENTAL- Bth-yl o-toluidinomalonafe is a colorless oil, reddening on standing, which dissolves in various organic solvents, and slowly reduces am- moniacal silver solutions or alkaline permanganate. I t s chlooride is a white or pink-white crystalline solid, m. p. 87'-go0, turning magenta in the light and funling in theair. Efhylnztroso-o-foluidi?~o- malonate, prepared by the action of nitrous acid upon either the above free base or its chloride, is a thick oil of a slightly reddish tint. Ethyl m-foZz~idinonialonate forms colorless needles, m. p. 50.5'-51~, I ts chloride crystallizes in rosettes of white, silky needles, m. p. 80'-83'. Ethyl nitroso-m-toluidinomalonate forms transparent, pinkish-amber prisms, m. p.. 58'-58.5', which be- come highly electrified when rubbed with a glass rod. Ethyl p-foluidinomaloonafe, a crystalline solid, has been described already by Blank. EthyZ nitroso-p-toluidizomalonafe is best purified by decomposing the pure sodium salt with carbon dioxide. I t is a clear, greenish yellow oil of the consistency of honey, turning slightly red on long standing. I t may be obtained in short, mono- clinic prisms by dissolving it in ligroin and letting the solution stand for a long time a t -15' ; but these crystals liquefy again very readily and are very soluble in all ordinary organic solvents.

On the Condensation of Oxalic Ethyl Ester with Ethylene and Trimethylene Cyanides. BY ARTHUR MICHAEL. Am. Chem I., 30, 156-163.-By the interaction of ethyl oxalate, ethylene cya- nide and sodium (or alcoholic sodium ethylate) ~ /3, y-dicyano-a,b- diketo a d i p i c e t h y I e s t e r, C,H,OOC . CO . C H ( CN ) . CH ( CN ) . CO. COOC,H,, was obtained. I t crystallizes in long, straw-colored prismsor in small, prismatic needles, m. p. 121'-123'. It is easily

M. T. BOGERT.

562 Reziew of Americaii Chemical Research.

saponified by boiling dilute HC1, giving a thick oil . Using tri- methylene cyanide instead of ethylene cyanide, the product w a s p,&- dz2yano.a-kefogl~~~aricester, ?JC.CH,.CH,.CH(CN) .CO.COOC,H,, which crystallizes from benzene i n nearly white, six-sided prisms, m. p. g6°-g50. Hydrochloric acidsaponifies it with lossof CO, and forniation of a thick oily acid. S o cyclic condensations could be obtained i n these reactions.

The Nitrosobenzaldehydes. BY FREDERICK J. XLWAY. Bey. d . chem. Ges., 36, 2303-23 I I .--p-H3'droxylanii?zobeliza~deAyde, HONHC,H,COH, is best prepared by reduction of the nitro alde- hyde with zinc dust, alcohol and glacial acetic acid. When its solution stands in the air, a red precipitate of the N-p-formyl- phenylether of p-azoxyhenzaldoxime gradually separates, its for- mation being greatly hastened by blowing a stream of air through the hot solution. Oxidation of the alcoholic solution o f j -hy - droxylnminobenzaldehyde with dilute sulphuric acid and potas- sium dichromate, or with I O per cent. ferric chloride solution, gives p-nitroso- andp-azoxy-benzaldehyde. But i f the hydroxyl- amino aldehyde, iu alcoholic solution, be mixed with caustic soda and shaken with air till the red color has disappeared, and then mixed with excess of hydrochloric acid, a precipitate of p-azoxy- benzaldehyde is obtained, colored slightly reddish by an impurity which is possibly the P-azobenzaldehyde. Heated in a test-tube, the azoxy aldehyde deconiposes with flame. S-/);fomzy&Ae?yl- ether of p'-nitrobenzaldorcii)ie,

O,NC,H,CH. NC,H,COH, \/ 0

11. T. BOGERT.

may be obtained from j-nitrobenzaldehyde, not only by electro- lytic reduction in concentrated sulphuric acid, or by reduction with zinc dust and acetic acid, but also by mixing its cold sul- phuric scid solution with a solution of p-hydroxylaminobenzalde- hyde. I t crystallizes from pyridine in brownish-yellow needles, ni. p. 224'. N-p-fovmyl~ke?~letAer of p-azox~,bcnzaldonime,

HOCC,H,N.CHC,H,N-XC,H,CH.NC,H,COH, v 0

was described in previous papers of the author, but Its structure has only just been discovered. I t may be formed : ( I ) 13y elec- trolytic reduction of the N-#-formylphenyletlier of p-nitrobenzal- doxirne in concentrated sulphuric acid solution, ( 2 ) by the action of oxygen or air upon p-hydroxylaniinobenzaldehyde, (3) by the action of zinc dust upon a glacial acetic solution of p-nitrobenzal- dehyde, (4) by condensation of j-hydroxylaminobenzaldehyde and #-azoxybenzaldehyde with sulphuric acid. On oxidation with ferric chloride or dichroinnte mixture, it gives p-iiitrosobenz-

\/ \/ 0 0

Organic Chemistry. 563

aldehyde and p-azoxybenzaldehyde. Pre#a?paiion of p-Nifroso- benzaldehyde from p-nitrobemaldehyde is carried out by reducing the nitro aldehyde to the hydroxylamino aldehyde, oxidizing the latter to a mixture of nitroso- and azoxybenzaldehyde, and driv- i n g over the nitroso aldehyde with steam. Reduction of the alco- holic solution of p-nitrobenzylchloride with zinc dust and acetic acid yields p-nitrosobenzaldehyde and not p-nitrosobenzylchloride. Reduction of m-nitrobemaldehyde with zinc dust, alcohol and acetic acid, leads to the formation of m-hydroxylaminobenzaldehyde, the N-m-formylphenylether of m-nitrobenzaldoxime, and a gray compound identical with the insoluble substance obtained by the electrolytic reduction of the latter. The crude reduction-product is oxidized and then distilled with steam ; m-nitrosobenzaldehyde passes over, while m-azoxybenzaldehyde remains in the flask. The action of$- foluidine upoiz p-nifrosobenzaldehyde gives p-azoxy- benzylidene #-toluidine, ON,( C,H,CH : NC,H,),. and ,b-folziene- azo-p-beizzylidene-p-tol~~i~ine, CH,C,H,N : NC,H,CH : NC,H,CH,. The latter crystallizes from benzene in orange-red leaflets, m. p. 17oO-171' (corr.); 27 per cent. nitric acid converts it top-toluene- azo-)-benzaldehyde, CH,C,H,N : NC,H,COH ; long, red needles, m. p. ~ 7 7 . 5 ' (corr.). M. T. BOGERT.

BY FREDERICK J. ALWAY AND ARTHUR B. W A L K E R . Ber. a'. chem. Ges., 36, 2312-2314,- The authors have prepared several esters of the 0-, m- and p-ni- trosobenzoic acids by reducing the corresponding nitrobenzoic esters with zinc dust, alcohol and acetic acid, oxidizing the hy- droxylamino compound thus formed to the nitroso state, and separating the nitroso ester from the azoxy body produced at the same time by the volatility of the former with steam. Like p-ni- trosobenzaldehyde, the p-nitrosobenzoic esters are green in solu- tion or when fused, but yellow in the solid state. EXPERIMENTAL. -o-Nifrosobenzoicmethylesfer, ONC,H,COOCH,, crystallizes from glacial acetic acid in colorless needles, m. p. 153' (uncorr.). T h e ethyl ester is a white powder, m. p. 120'-121' (uncorr.). m-Nifrosobeizzoicmethy/ester ; white crystals, ni. p. 93' (corr.). m-Azoxybenzoicmefhy/esfer, ON, ( C,H,COOCH,),, crystallizes from glacial acetic acid in orange needles, m. p. 136'-136.5' (corr.). P-Nitrosobenzoicmefhylesfer ; straw-colored needles (from alcohol), m. p. 128~-129.5' (corr. ) , p-Azoxybenzoicmefhylesfer ; red needles (from alcohol), m. p. 206.5'-207.5' (corr.), the red color being probably due to a trace of the azo ester.

The Nitroso Benzoic Acid Esters.

M. T. BOGERT. m-Nitro-Nitrosobenzol. BY FREDERICK J. ALWAY. Ber. a'.

chem. Ges., 36, 2530-2 531 .-If m-dinitrobenzene be reduced with zinc dust, alcohol and acetic acid, the reduction mixture oxidized with ferric chloride and then distilled with steam, m-nitro-7zifroso- benzene passes over. Recrystallized from alcohol, it appears as a

564 Review of Americuz Chemical Reseavch.

nearly white or blue-green powder, in. p. 85' (corr.). In one case, long, blue-green needles, m. p. 81'-82' (corr.), were ob- tained. I t unites with aniline to form m-nitroazobenzene.

As to the History of lsocinnamic Acid. BY X K , r m R MICHAEL. Bey. d. chem. Ges., 36, 2497-2498.-A reply to a recent article by Liebermann (Bev. d . chenz. Ges., 36, 1448 (1903) j . The author explains that further work upon isocinnamic acid has been de- layed by the inipossibility of reproducing the acid of in. 1). 36', in spite of many attempts. Attention is called to certain facts observed by Liebermatin, in the latter's investigation of the same subject, for which a satisfactory explanatioii is still lackiiig.

M. T. BOGEKT.

11. T. BOGERT. On Some Pseudodithiobiurets. BY TxEaT BALDWIN JOHN-

SON. Am. C'hem. ]. , 30, 167-182.-Pseudothioureas, HS : C(SR) .NH,, combine smoothly with isothiocyaiiates to give a new class of pseudodithiobiurets, RNHCSN : C(,SR) NII,. JIethyl iodide unites with certain of these dithiobiurets to form dipseudo- ditliiobiurets. R N : C(SR)NHC(SR) : NR. Phenylhydrazine only removes the isothiocyanate from the ditliiobiurets, leaving di- phenylthiosetnicarbazide, and does not cause the formation of any triazole bodies. The nitrogen and sulphur atoms in the biurets

I ( a ) ( 1 ) ( 6 ) (2) (('1

are indicated as follows :-X : C(S-)N.C(S--,S : E X P E K I -

ME~WAL.-( By Howard S. Bristol). n-Phenyl-r-fhio(ii~efh~il~sezL- dodifhiobiuret, C,H,N : C(SCH,)NHCSPJH,, prepared by Tursini's method from phenyldithiobiuret, methyl iodide and ammonia, crystallizes from alcohol in long prisms, in. p. 122'. a-Phezill-2- thiolnteth;t/~seudodithiobiuret, from phenylisothiocyaiiate and thiol- methylpseudothiourea ; prisms (froin alcohol), melting with effer- vescence at I 24 ' . a - Pheiz yl- 2- f k i o l e f k y ~ ~ s e ~ ~ d o ~ i f h iobiuret, from phenplisothiocyanate and thiolethylpseudothiourea : tables, ni. p. I 14'. p- Tolyl-thioCirzefh_z~~seudotkioureu, C,H,N : C(SCH,)XH,, crystallizes from petroleuni ether in plates, in. p. 6jo-67'. Its hydriodide is formed by the action of methyl iodide upon p-tolyl- thiourea, and melts with effervescence at 129'-130'. With phenylisothiocyanate, the free base unites to n,p-fool3,l-c-phenyl-r- thiol?neet/2y~seudodif~iobiuret, crystallizing from alcohol in prisms, ni. p. 93'. This in turn combines with methyl iodide to form a,p-fol3,l-c-pheiiyl-r,a-t/2io I m e f h y l d i f i sezsdoLZifhiobiuref, C,H,N ; C(SCH,)NHC(SCH,): NC,H,, which separates a s the hydriodide; colorless prisms (from alcohol), melting a t 164' with effervescence. The free base is an oil. a$- Tolyl u -mef~y l th io lmef~y~seudofh io- urea was obtained as the hydriodide by allowing methyl iodide to act on P-tolylthiolmethylpseudothiourea, and melts a t 19oO-191

Organic Chem is fry. 565

with effervescence. The free base is oily. From this pseudo- thiourea and phenylisothiocyanate there was produced a,p-to&Z- a-methyl-c-PAenyl-z-fhiolmethyZpseudodiit ; prisms (from al- cohol), m. p. 124'. The hydriodide forms minute prisms, melt- ing sharply at 182' with effervescence.-(By Morgan s. Elmer). a , c - Dz;bhenyl- z - tlz ioZmefhy~seudodiobiuYef , from phen ylt hiol- methylpseudothiourea aud phenylisothiocyanate ; transparent prisms (from alcohol), m. p. IOI '. ThioZmethyZester ofphenyZthio- allophanic a d , C,H,NHCSNHCOSCH,, was obtained by heating a,c-diphenyl-r-thiolmethylpseudodithiobiuret with jo per cent. hydrochloric acid ; plates (from chloroform), melting sharply at I j 7 O- I j8 ' with effervescence. a , c-Diphenyl- r, a- fhiolmethyldi-

Psezidodithiobiuret. Its hydriodide results from combining methyl iodide with a,c-diphenyl-1-thiolmethylpseudodithiobiuret, and crystallizes from alcohol in stout prisms, melting with efferves- cence at I 54'-I j j'. The free base forms colorless needles (from alcohol), m . p. 103 '-104': a,c-~~henyl-a-met~yl-z-thiolmethyZ- pseudodithiobiuret, from a-phenyl-a-methylthiolmethylpseudothio- urea and phenylisothiocyanate ; stout prisms (from alcohol), ni. p. 133'-134'. a,c-D~heiiyl-r-thioolbenzy~seu~odifhi~biuyef, from phenylthiolbenzylpseudothiourea and phenyl mustard oil ; colorless prisms (from alcohol), m. p. 98'-100'. Benzoyl isothio- cyanate a?~dphenylthiolbenzy~seudothioziyea react to produce a solid substance, crystallizing from benzene in yellow prisms, m. p. 190'- rgr ', apparently a triazine derivative.-(By William B. Cramer). o-Tolylthiolmethylpseudothiourea was prepared from o-tolylthio- urea and methyl iodide, and the product proved to be identical with that already described by Dixon. With phenylisothiocy- ana t e, it yields a , o-fo&Z-c-Phenyl-r -thioZmethyy(pseudodirhio biuret ; plates (from alcohol) m. p. i14'-115'. Methyl iodide unites with it to form the hydriodide of a,o-folyZ-c-phenyZ-r,z-fhiolmefhyl- di~scudod~thiobiuret, which melts with effervescence at 147 '-148'. The free base crystallizes from alcohol in prisms, m. p. 70O-7 I '. a-Phei~Z-c,o-fo~l-z-thiolmethyy(pseudodifhitltlobiuvet, from o-tolyliso- thiocyanate and phenylthiolmethylpseudothiourea, crystallizes from alcohol in plates, m. p. 114'-115'; combined with methyl iodide, and the product treated with caustic soda, a,o-tolyl-c- phenyl- I, 2-thiolmethyldipseudodithiobiuret is obtained. a,o- ToZyZ- c-phenyl-r-thiolethyy(pseudodithiobiut-et, fron phenyl mustard oil and o-tolylthiolethylpseudothiourea, crystallizes from dilute alcohol in plates, m. p. 117'-118'. Warmed with 50 per cent. hydrochloric acid, this biuret yields #henylthioallophanic acid thiolethylesfer ; plates (from alcohol), m. p. 131'-132'. a-Pheizyl-c,o-tolyl-r-thioZ- e thy~seudod i th iob i~~e t , from phenylthiolethylpseudothiourea and o-tolylisothiocyanate, crystallizes from alcohol in plates, m. p. 9 5'-96'. By using phenylisothiocyanate, instead of the o-tolyl- i so t h iocy an a te, a , c- diphen y I- z-thiolethy~seildodilhio biuret is ob- tained; plates (from alcohol), m. p. g1O-93'. a,c-Di-o tolyZ-z-

566 Review of Anzericaii Chemical R e s e a i d .

t/Eiolet/Ey~seudodif/Eiobiuvet, from 0- tolylisothiocyaiiate and 0. tolyl- thiolethylpseudothiourea, crystallizes from alcohol in prisms, ni . p . 86 O -8 7 O. a , c-Di-o- foolyl-r- th ioline f hy Qseudodith iobiuret from o-tolylisothiocyanate and o-tolylthiolmethylpseudothiourea ; plates (from alcohol), m. p. 1 2 2 ~ - 1 2 3 ~ .

The Action of Acetyl Chloride upon Selenic Acid. BY ARTHUR B. LAMB. Am. Cllem. f., 30, 209--212.-By the action of acetyl chloride upon selenic acid, selenium tetrachloride is formed. hl. T. BOGERT.

M. T. BOGERT.

BIOLOGICAL C H E f i l S T R Y . Experiments on the Digestibility of Vegetables, By A. P.

BRYANT AND R. D. MILNER. Am. /. PhysioL., IO, 81-1oo.-The vegetables studied were the potato, the beet, cabbage, and green corn, also apple sauce. The results indicate that so far as sources of proteid or fat are concerned, the regetables studied may be con- sidered of little value. The carbohydrates that they contain ap- pear to be quite well digested and absorbed, and they may, there- fore, be considered as of value a s sources of energy, a large pro- portion of which appears to be available to the body. The chief value of many vegetables is, perhaps, that aside from the nutrients or energy they furnish, they add a pleasing variety and palata- bility to the diet, supply orgairic acids and mineral salts, and give the food a bulkiness that seems to be of importance i n its mechan- ical action in maintaining a healthy activity of the alimentary tract. The result of these conditions is a favorable influence upon the digestion of other food eaten with the vegetables.

F. P. ENDERHILL. On the Digestion and Self-digestion of Tissues and Tissue

Extracts. BY P. A. LEVENE AND L. B. STOOKEY. f. iMed. Research, IO (New Series, 5 ) , zr7--2z8.--In the present research, an investigation of the following points was attempted : Whether the inhibitory action of a tissue on trypsin or pepsin is exercised by its cells or by their soluble constituents. Whether the tissue extracts exercise an inhibitory action on the proteolytic enzymes of other tissues-on the intracellular enzymes. Whether the in- hibitory action of the blood a i d tissues can be increased by means of immunization. The results show that unboiled extract of liver, spleen, blood, egg white, etc., is digested hy pancreatic extract slower than one that has been heated previous to the experiment, that the strength of the digestion depends upon the quantity of the enzyme added ; that in the pancreatic extract and in the white of the egg there is an inhibitory action against the intracellular enzymes, and that the blood of immunized rabbits offers a mark- edly higher resistance toward tryptic digestion than that of the normal animal. F. P. UNDERHILL.