ofPyroxylic Sjnrify and of iU derived Combinations, 117 



dually rises to 70° or 80° centigrade. The liquors of different 

 boiling points must be separated. In the first portions are 

 found some aldehyd, but principally a new and peculiar fluid, 

 to w hicli the name formal can be applied, from considerations 

 which shall hereafter be brought forward. The latter portions, 

 which boil from 60° to 70°, consist of Dumas's pyroxylic spirit, 

 together with small quantities of a fluid identical with that py- 

 roxylic spirit originally analysed by Liebig, and to which I 

 shall again recur. 



The formal, obtained pure by rectification over chloride of 

 calcium, is colourless, and of a penetrating but aromatic odour ; 

 it mixes with water in every proportion, from which it is sepa- 

 rated by the addition of chloride of calcium ; the separation is 

 however by no means perfect. Pure formal boils at 38° cen- 

 tigrade. Subjected to analysis, 

 (No. 1.) 0*502 material gave 



Water = 0*428 

 Carbonic acid = 0*833, 

 (No. 2.) 0-528 material gave 



Water = 0*441 

 Carbonic acid = 0*875 ; 

 from whence follows. 



No. 1. No. 2. 



Carbon = 45*87 45*82 



Hydrogen = 9*47 9*28 



Oxygen = 44*66 4490 



100- 00 100 00 



with which agrees the formula 



4 atoms carbon = 305*89 45*77 



10 hydrogen 62*39 9*34 



3 oxygen 300*00 44 89 



668*28 100*00 



To confirm this analysis by the density of the vapour the 

 following experiments were made : 



(No. 1.) Weight of balloon with air = 37*244 grammes. 



vapour = 37*520 



Excess = 0*276 grammes. 

 Volume of balloon = 266*5 cub. cent. 



Residual air 2*5 cub. cent. 



Temperature of air 16*8 cent. 



Temperature of vapour 97*75 cent. 

 Barometer 0*750 metre. 



From whence results, 



