90 Ixnyal Soc'wttj of Londov. 



organic matter, which cannot be discriniinalc'd from their 

 comtc or tails. 



June II. The president in the chair. — An interes'ing 

 paper on the quantity of oxygen in carbonic acid, bv JN-lessrs. 

 Pcpys and Allen, occupied the attention of liie society. These 

 expert analysts preferred ihe u-^e of charcoal to that of dia- 

 mond for this purpose, as tbcy conceived that very niaierial 

 errors existed in Guyton's experiments on this subject. Tlicy 

 began with preparing: charcoal from the diffL;rent species of 

 wood, by burning it in a platina tube, and, as usual, tlie 

 woods yielded more or less charcoal according to their par- 

 ticular qualities and densities. This charcoal, when taken 

 trom the platina tubes and exposed to the atmosphere, ab- 

 sorbed water in (juantities varying from 5 to IS percent., 

 according to the nature of the wood from which it was 

 made. The water of absorption was afterwards dispelled in 

 vapour, without being decomposed, or giving; out oxvgen or 

 hydrogen to the carbon. Carbonic acid was then prepared 

 from this charcoal, which yielded to the acid, in different 

 specimens, fionr 27-00 to 28 GQ per cent, of carbon, the 

 oxygen varying in the same proportions. Diamond was 

 next exannned, a)id it vielJed I'SSC per cent, carbon, with 

 an equal proportion of oxyeen in the formation of carbonic 

 acid. Fknce it was concluded, that allhougli tliC results of 

 these experiments d ffer a little from the (piantitv of carbon 

 supposed to be contained in carbonic acid, according to ]\fr. 

 Tennant's experiments, vet it was evident that the diamond 

 cannot be peculiarly an oxide of carhv)n, as has been al- 

 leged, since tlic oxvgen consumed in th.e conversion of the 

 carb<Mi fo acid was uniformly in proportion to the (piantiiy 

 of carbon emploved. In the course of the experiments 

 with the diamoiid, the authors conceive that no hydrogen 

 was present, neither was there with the plumbago and dead 

 coal, and the water absorbed by charcosl exposed to the 

 air, was evaporated on exposure to a sufficient degree of 

 temperature. To ihe accuracy of"Guvt>)n's experiments 

 t}iey particularly objected, and considered them as incon- 

 clusive and erroneous, especially in his use of uilrogen gas 

 as a test for the oxygen. 



June 



