70 Scientific Intelligence. [JtJLY, 



evaporate the aqueous solution to dryness in order to obtain the 

 picromel in a state of purity. 



It is a greenish-yellow matter, soluble both in water and alco- 

 hol, and having very much both of the aspect and of the taste of 

 sarcocoll. When heated to redness with a sufficient quantity of 

 peroxide of copper, the only gas which comes over is carbonic 

 acid. If the gas has been made to pass through dry muriate of 

 lime, the salt will have acquired a slight increase of weight, indi- 

 cating the formation of a little water. From the analysis of 

 picromel performed in this way, it appears that its only consti- 

 tuents are : 



Oxygen, 



Carbon, 



Hydrogen. 



One grain of picromel heated with 140 grains of peroxide of 

 copper yielded 4*2 cubic inches of carbonic acid gas under the 

 mean pressure and temperature, and the water formed weighed 

 0-2 gr. 



Now 4-2 cubic inches of carbonic acid gas weigh 1-95 gr. and 

 contain 0*531 gr. of carbon: 0*2 gr. of water contain 0*022 gr. 

 of hydrogen. Hence the constituents of picromel are : 



Carbon 0*531 



Hydrogen 0*022 



Oxygen 0*447 



1-000 



The smallest number of atoms which correspond with these 

 proportions are the following : 



5 atoms carbon = 3*750 54*53 



1 atom hydrogen = 0*125 1*82 



3 atoms oxygen = 3*000 43*65 



6*875 100*00 



These proportions do not exactly coincide with the experimen- 

 tal results, but the difference does not amount to one per cent. 

 The proportion of carbonic acid gas stated above is the mean of 

 five experiments, and cannot I think deviate far from the truth, 

 I am not so well satisfied with respect to the quantity of water. 

 It varies according to the rapidity of the evolution of the gas, 

 and according to the quantity of heat communicated to oxide of 

 copper. The variations all he between two atoms of hydrogen 

 and one atom. Perhaps, therefore, the true quantity of hydrogen 

 in picromel may be two atoms. This must be determined by 

 future experiments. 



We see from the above analysis, that picromel differs from 

 sugar and gum in containing a much smaller proportion of 

 hydrogen. The absence of azote gives it rather the character 

 ©fa vegetable than an animal substance. 



4 



