3 o CHEMICAL CONSTITUENTS OE BODY AND FOOD. 
compounds of this substance, but, as Liebig 1 was the first to show, 
this work was full of fallacies, and the only remnant of it is the survival 
of the word proteid. 
Pavy 2 has used caustic potash in his researches on proteids, and 
shown that the action of the alkali is to split offa substance of an amylose 
nature which, on further treatment with mineral acids, yields a reducing 
but non-fermentable sugar, C H 12 O G , which gives a crystalline osazone 
with phenylhydrazine. Pavy, however, himself points out that he is 
not the first to obtain this result. Schiitzenberger 3 many years ago 
obtained from proteid a dextrin-like substance by the prolonged use 
of baryta water, which, after treatment with sulphuric acid, reduces 
Fehling's solution, and " appears to be glucose, or an analogous substance." 
From his own and Schiitzenberger's work, he draws the conclusion that 
proteid matter has the constitution of a glucoside. These experiments 
will be again referred to under the gluco-proteids. 
0. Nasse 4 discovered that by boiling proteids with a strong solution 
of barium hydrate some of their nitrogen was disengaged as ammonia, 
but this only accounted for a small percentage of the total nitrogen. 
He concluded that the nitrogen which is readily liberated is in the form 
of an amide, that some is combined similarly to that of creatine, but that 
the major part which is unaffected by this treatment is in the form of 
an amido-acid. 
Schiitzenberger 5 has elaborated the baryta method. He obtained dif- 
ferent results by varying the conditions of temperature and pressure, of 
the time of treatment, and of the amount of barium hydrate employed. In 
his earlier researches he employed coagulated egg-white, which had been 
thoroughly washed with water, alcohol, and ether; weighed amounts of 
it were treated with from two to six times then* weight of crystallised 
barium hydrate and with water, the whole being heated in a closed iron 
vessel to temperatures ranging from 100° to 250° C, and for periods of 
time varying from 8 to 120 hours. He found that nitrogen to the extent 
of about one per cent, of the total weight of albumin is given off as 
ammonia at atmospheric pressure, by boiling for half an hour; a second 
one per cent, comes off slowly by continued boiling for 120 horns (this 
result is, however, more easily obtained by treating with three parts of 
barium hydrate at 120° C. for six to eight hours) ; a third one per cent, is 
given off by treating with two parts of barium hydrate at 150° C, and a 
fourth one per cent, by heating with excess of barium hydrate at 260° C. 
He next found that accompanying these four stages there were 
different cleavage products obtained. First, some insoluble barimn salts, 
namely, oxalate, carbonate, phosphate, and sulphate. On calculating 
the quantities of oxalate and carbonate formed, he arrived at the 
interesting result that they were present in proportions to support the 
hypothesis that, with the ammonia set free, they had existed in the pro- 
teid molecule as a urea and oxamide radicle. The barium carbonate 
and oxalate, moreover, were formed at different stages of ammonia 
1 Ann. d. Chcm., Leipzig, Bd. lxii. S. 132. 
2 "Physiology of the Carbohydrates," London, 1894, p. 28; Proc. Buy. Soc. 
London, 1893, vol. liv. p. 53 ; Rep. Brit. Ass. Adv. Sc, London, 1896. 
* Butt. Soc. chim., Paris, 1875, Se>. 5, tome xxiii. p. 161. 
4 Chcm. Centr.-Bl. Leipzig, 1873, S. 137; Arch./, d. ges. Physiol., Bonn, Bde. vi. S. 
589 ; vii. S. 139 ; viii. s. 381. 
5 Ann. dechim., Paris, Ser. 5, tome xvi. p. 289 ; Compt. rend. Acad. d. sc, Paris, tomeci. 
p. 1267 ; cii. p. 289 ; cvi. p. 1407 ; cxii. p. 189 ; Bull. Soc. chim., Paris, Ser. 5, tome xxiv. 
