408 STUDIES ON THE PHENOMENA OF CONTACT. 



It has quite lately been placed bciyond doubt that there are three bodies 

 present in this pluMiomenon, to wit : oxygen, sugar of milk, and a peculiar fer- 

 ment. M. Pasteur, in effect, has recently isolated a body which he calls 

 laci'/c ferment, and which, in his opinion, is the principal cause of the lactic 

 fermentation. It is a gray and flocculent substanc(.', which jirocceds, without 

 doubt, from the caseine. The lactic fermentation, therefore, would be altogether 

 analogous to the alcoholic fermentation but with another ferment. 



Willi regard to the viscous and butyric fermentations, &c., I have nothing to 

 add to what is already known respecting these phenomena — which is very little. 

 Respecting eremacausis (the slow combustion of organic substances by oxygen 

 at the ordinary temperature) or putrefaction, we have already seen how it is 

 induced, and how it is always accompanied with the production of ozone. 



It nnuains to speak now of the action of acids on organic bodies, for, in this 

 action it has becai often su])posed that catalytic phenomena were distinguishable. 

 When an organic substance is treated with an acid it often happens that this 

 acid oxidizes it Avhile it is itself decomposed, such bci)ig the case when sugar, 

 &c., is treated with azotic acid, sulphuric acid, &;c. At other tinujs the acid, 

 or a derivative of the acid, combines with the body, either after having oxidized 

 it or directly. We observe this when we treat cellulose with concentrated 

 nitric acid. At other times, again, the oxide? of a radical compound is formed 

 in the action of the acid on the organic body, with which the deoxidized 

 acid combines, as may be seen when hyponitric acid reacts on the oxides of 

 certain radical compounds which may become peroxidized, and themselves unite 

 in this state with the nitrous acid, giving rise to nitrites ( IK) + AZ()^i=llO^AZO''.) 

 In fine, when acids arc added to organic bases, or to alcohols, there arc formed 

 salts, or compound ethers, which are also salts. In these two cases the acid 

 replaces the Avater of the base or of the alcohol. There are, however, cases 

 where acids occasion a change of a wholly different kind, and give rise to jiroducts 

 which may be termed abnormal. 



Such is the case where; sulphuric acid acts on fecula or on cellulose producing 

 sugar. In this case the influence of contact has been seen, and many 

 chemists have suppgsed that the sulphuric acid acts only by its presence, and 

 that the fecula combines wife-h a certain quantity of water to produce sugar. It 

 is, however, not so ; the action of sulphuric acid on starch or cellulose ap- 

 pears to be altogether analogous to the formation of ether by the action of 

 this same acid on alcohol. In this latter case there is, as we know, the formation 

 *)f an intermediary compound, sulpho-vinic acid, which, by the action of heat, 

 separates into ether and free sulphuric acid. Now, sulphuric acid forms with 

 starch or cellulose, an analogous compound, sulpJio-lignic acid, which, like 

 sulpho-vinic acid," forms soluble salts with lime and barytes, and separates 

 by ebullition into sugar and free sulphuric acid. The sulpho-liguic acid can- 

 not be formed except at the ordinary temperature. If the temperature be raised 

 we obtain other products, sulphuric acid is then decomposed, and produces, 

 ^vith th{! cellulose, &c., brown substances resembling huinus. 



The diastase of sprouted barley gives rise to the same phenomenon as the 

 sulphuric acid in the former case, namely, the production of glucose, but this 

 is accomplished in a diffei^ent manner. According to ;dl appearance the trans- 

 formation is here direct. There is no intermediate combination ; but the cir- 

 cumstances of that remarkable modification which the stai'ch undergoes from 

 contact with the diastase are still very incom})letely known. It would seem, 

 iiowever, that the diastase acts as v^ ferment, (as the ferment, for exaia})le, in 

 the alcoholic fermentation;) and M. Magendic has observed in this connexion 

 that blood, bile, urine, sperm, &:e., in a word, the other ferments act like 

 the diastase. Starch, in these circumstances, is first transformed into dextrine, 

 then into glucose. It is highly probable that hereafter it will be discovered 

 that the presence of a third body is essential to this pheuomeiion, and that 



