Messrs. Cross and Be van on Pseudo- Carbons. 327 



exact representation. The ultimate solution of these problems 

 cannot, therefore, be more than indicated; and it is thrown upon 

 the experimentalist to supply the requisite data. It is an 

 interesting fact that as early as 1805 Hatchett* published the 

 results of an investigation of the action of nitric acid upon 

 these pseudo-carbons, in -which he established, as a general 

 property, that they are by this action converted into soluble 

 bodies having the astringent and other characteristics of the 

 tannins. His results are, it is true, of a somewhat empirical 

 and qualitative order : they are nevertheless worthy of much 

 more attention than they have received; and their recognition 

 would have kept prominent the compound character of the 

 pseudo-carbons. It is noteworthy that Berzelius t was suffi- 

 ciently impressed with their importance to devote consider- 

 able space in his treatise to their reproduction. Modern 

 writers, on the other hand, have ignored them, probably from 

 a sense of their lacking theoretical coordination. Hatchett 

 himself appears conscious of this, and also of some virtue in 

 undertaking the investigation of these bodies — the products 

 of the action of the acid, — from which, as he says, chemists 

 have doubtless been deterred, or even repelled with disgust, 

 by reason of the " proteus-like " changes which they undergo 

 whilst under experiment. 



In ignorance of his results, we were led to investigate cer- 

 tain of these pseudo-carbons, from the altogether different- 

 standpoint of their relationship to the carbohydrates. The 

 black "carbonaceous" substance which we obtained i by the 

 action of sulphuric acid at 70° C. upon cellulose, we found to 

 be converted by the action of chlorine into a bright yellow 

 chlorinated substance, soluble in alcohol, and resembling in 

 composition and properties the product of the action of this 

 gas upon the jute-fibre substance — the latter being an un- 

 doubtedly aromatic derivative, having many points of resem- 

 blance to tetrachloroquinone, and standing in close relation- 

 ship to the natural group of astringents or tannins. It is 

 not our intention to reproduce the long synthetical proof by 

 which we sought to establish, from the chemical side, the de- 

 velopmental connexion of the tannins with the carbohydrates. 

 Suffice it to say that the most direct point in the proof lay in 

 the chemical characteristics of these pseudo-carbons: and from 

 a study of these, as yet only superficial, we are impressed with 

 the relations of both to the carbohydrates, the connexions 

 being completed through infinite series of naturally-occurring 



* Phil. Trans. 1805. 



t Traite de Chimie (translated from 4th German ed., by Valerius), iii. 

 p. 218. % Brit. Assoc. Eeports, 188L 



2C2 



