1815.] Elements of Organic Nature are comlined. '^Vf<) 



are all composed of a small number of volumes, compared n'lth 

 those that are to follow ; so that the addition of a single volume or 

 atom of one of the elements would produce a great change in the 

 composition. This is the reason why the greater number of 

 vegetable acids do not constitute genera of analogous substances 

 having the same general character, but differing in some points, so 

 that they must be considered as ditferent species of the same genus. 

 There is only one acetic acid, one gallic acid, and wherever these 

 bodies occur in the vegetable kingdom they constitute absolutely the 

 same substance. 



As the number of volumes increases in the ternary oxides, they 

 acquire the property of producing a certain number of varieties, or 

 of different species of the same genus, which appear to owe their 

 origin to the adhesion of one or more volumes of one of the 

 elements. This addition, however, in consequence of the great 

 number of volumes of the element contained in the substance, only 

 produces an insensible alteration in its composition when we con- 

 sider 100 parts only. 



We have, then, various species of tannin, gum, sugar, &c. 5 

 and I have placed the analysis of mucous {saclaclk) and benzoic 

 acid among the substances which form genera and species, because 

 I think it probable that there are other acids differing from them 

 only as different species. 1 have found, for example, that 

 sebacic acid found in the products of the distillation of fatty sub- 

 stances possesses all the chemical characters of benzoic acid ; but 

 that it varies from it a little, owing, I supposed, to the presence of 

 foreign bodies, from which I was unable to free it. It is possible 

 that it may differ from benzoic acid, as the tannin of the oak does 

 from that of catechu, or oi the arbutus uva ursi. 



1 shall not attempt at present to determine the difference of 

 composition of the species. Such experiments appear too delicate 

 to be executed with success before the generic differences are 

 known. To them, therefore, 1 have directed my first eflbrts. 



7- Mucous Acid {Saclactic ylcid*). — Mucate of lead is easily 

 decomposed at a temperature whicli does not act upon other 

 vegetable salts. It becomes brown ; and when afterwards treated 

 with ammonia, this alkali acquires a yellow colour. The same 

 thing happens to the pure acid. Much circumspection is, therefore, 

 requisite, hi order to obtain these substances sufliciently dry, without 

 having undergone any decomposition. 



A hundred parts of mucate of lead, analyzed by cotnbustion, 

 gave from 51-4 to 51'C6 of oxide of lead. Hence 100 acid saturate 



* The uamc mucou* a<,id it very iinproprr, bccnutc it indicates an acid iaoiia, 

 whirh c.'inriot exist Without one in U \\\\\\ tlic same indidc. I huvo not, iiowcVcr, 

 ▼mtiirrd to chaiiRc it, bocnusc muric ucid n^iglil, I llionglit, ;iiij)f;ir lidiculuus. 

 lit Mita, liowrviT, 1 thall call miiiiitcti. 



1 Hondn Dr. It^-riEcliiis did not lliii)k uf having rrrearse to (li<^ nM mwnc aao- 

 larth oiiri, wliiili i^i very prosier, :iiid rci.'ilU the hi.ilory «f its original discovery, 

 I hnve uted it ever linci- I wdi aware of thoabiurditj of tht term mucous.— 1\ 



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