No. 2.] BRITISH ASSOCIATION MEETING. 165 



subject, it may be interesting to recal the experiments of Pelouze 

 and Cahours on the Pennsylvanian oils, which proved to be a 

 mixture of carbolizdrogers belonging to the marsh gas series. 

 An elaborate exposition of Berthelot's method of transforming 

 an organic compound into a hydrocarbon containing a maximum 

 of hydrogen, has appeared in a connected form. The organic 

 body is heated, in a sealed tube with a large excess of a strong 

 solution of hydriodic acid, to the temperature of 275°. The 

 pressure in these experiments Berthelot estimates at 100 atmos- 

 pheres, but apparently without having made any direct measure- 

 ments. He has thus prepared ethyl hydride from alcohol, alde- 

 hyde, &c., hexyl hydride from benzol. Berthelot has submitted 

 both wood charcoal and coal to the reducing action of hydriodic 

 acid, and among other interesting results, he claims to have ob- 

 tained in this way oil of petroleum. By the action of chloride 

 of zinc upon codeia, Matthiessen and Burnside have obtained 

 apocodeia, which stands to codeia in the same relation as apomor- 

 phia to morphia, an atom of water being abstracted in its forma- 

 tion. Apocodeia is more stable than apomorphia ; but the action 

 of reagents upon the two bases is very similar. As regards their 

 physiological action, the hydrochlorate of apocodeia is a mild 

 emetic, while that of apomorphia is an emetic of great activity. 

 Other bases have been obtained by Wright by the action of 

 hydrobromic acid on codeia. In two of these bases, bromotetra- 

 codeia and chlorotetra-codeia, four molecules of codeia are welded 

 together, so that they contain no less than seventy-two atoms of 

 carbon. They have a bitter taste, but little physiological action. 

 The authors of these valuable researches were indebted to Messrs. 

 Macfarlane for the precious material upon which they operated. 

 We are indebted to Crum Brown and Fraser for an important 

 work on a subject of great practical, as well as theoretical, inte- 

 rest — the relation between chemical constitution and physiological 

 action. It has long been known that the ferrocyanide of potas- 

 sium does not act as a poison on the animal system ; and Bunsen 

 has shown that the kakodylic acid, an arsenical compound, is also 

 inert. Crum Brown and Fraser found that the methyl compounds 

 of strychnia-brucia and thebaia are much less active poisons than 

 the alcoloids themselves; and the character of their physiological 

 action is also different. The hypnotic action of the sulphate of 

 methyl-morphium is less than that of morphia. But a reverse 

 result occurs in the case of atropia, whose methyl and ethyl deri- 

 vatives are much more poisonous than the salts of atropia itself. 



