196 ANNUAL OF SCIENTIFIC DISCOVERY. 



new organic acid, for pure silica, and suggested whether siliciotis 

 compounds occurring in nature, and containing organic matter, 

 might not actually hold the same in chemical combination. The- 

 nard, in the same connection, referred to researches recently 

 made by him on silico-organic acids, of which he has prepared 

 several, varying in their percentage of silica from 7.5 to 24 per 

 cent. The process of preparing these compounds is an indirect 

 one. Ulmic acid is treated with ammonia, and a nitrogenous acid 

 formed which possesses the property of readily combining with 

 silica to produce a compound soluble in caustic alkali, from which 

 it can again be isolated unchanged by the addition of a mineral 

 acid. The quantity of silicon entering into these compounds 

 seems to be proportional to the amount of nitrogen originally 

 held in combination. The author is led to believe that there 

 always exist in soils these silico-organic acids, and that they play 

 a very important part in the nutrition of plants. He regards the 

 action as different from the property already noted by Verde il and 

 Rislher, by which sugar and other non-nitrogenous organic 

 bodies dissolve up small quantities of silica ; nor does he confound 

 the silicated organic compounds (organo-silicatees) with the com- 

 pounds described by Friedel, in which silicon plays the part of 

 carbon. Still, we have no right to assert that the former may not, 

 in nature, lead to the latter, and the author thus explains the 

 origin of the silicon which attacks a platinum crucible when used 

 for the calcination of rich soils. Comptes Eendus. 



Chemical Geogony of Silica. In the American " Gas-Light 

 Journal," for September 2, 1870, Professor Henry Wurtz thus re- 

 marks on the papers of Friedel and Thenard : "We have 

 thus demonstrated at once a theory not only of new relations of 

 plant decay to plant nutrition, but also of the far broader subject 

 of the transformations and migrations of silica throughout all past 

 geological ages, and of the continual and (as the writer has long 

 believed) sole agency of life in these, as in the past and present 

 migrations of carbon." 



Prof. Wurtz presented a preliminary paper " On the Chemical 

 Geogony of Silica," to the New York Lyceum of Natural History, 

 in which he says : 



" The importance of the function of soluble and hydrated forms 

 of silica in mineral fertilizers, like green sand, has been under- 

 rated. Silicic acid, though so minute an ingredient in actual 

 animal nutrition, is indirectly as essential to animal life as even 

 carbonic acid." By the application to the past history of silicic 

 acid of the same process employed by the author in tracing out 

 the anterior stages of the chemical changes now going on in the 

 case of carbon and oxygen (see various papers in the Proceed- 

 ings of the American Association), Prof. Wurtz believes that his 

 studies have unmistakably tended toward the conclusion that silicic 

 acid, as such, that is, in isolated forms, appertains, in origin at 

 least, altogether to the vegetable kingdom, and that the tendency of 

 chemical investigation and discovery is to confirm this conclusion. 

 He presented to the Lyceum a diagram illustrating his view of 

 the changes undergone (see also the "American Chemist "for 



