NITRIC ACID ON VARIOUS VEGETABLES. 
419 
Basic Nitro'pofulate of Baryta. 
This salt is obtained by adding a hot solution of caustic baryta to a hot solution of 
nitropopulic acid, so long as a precipitate is formed. This precipitate, which consists 
of very minute crystals, must be immediately collected on a filter and thoroughly 
washed with boiling distilled water, in which it is nearly insoluble. It was also first 
dried in vacuo. When it was afterwards heated in the water-bath to 212 ° Fahr., it 
did not lose any weight. 
0-241 grm. salt gave 0-151 BaO 803 = 0-0991 BaO=41-12 per cent. 
Calculated numbers. Found. 
C 14 1050-00 
H 3 37-50 
N 2 350-50 
O 13 1300-00 
BaO 2 1909-00 41-08 4T12 
4647’ 
The formula of this salt therefore is C, 4 H 3 N 2 0 i 3 (BaO) 2 . 
Nitropopulate of Lead. 
Both the neutral and basic lead salts of nitropopulic acid may be readily obtained 
by treating a hot solution of the potash salt with neutral or basic acetate of lead. 
Both of these lead salts are uncrystallizable and insoluble in water. 
Populus nigra. 
As I was anxious to ascertain if nitropopulic acid could likewise be obtained from 
the various other species of Poplar as well as from the Populus halsamifera, a quan- 
tity of the small branches of the Populus nigra cut into pieces, boiled with water, 
and the solution concentrated to the state of an extract, exactly in the way already 
described. This extract was also digested with dilute nitric acid. The products were 
found to consist chiefly of an acid, having all the external characters of nitropopulic 
acid, together with a considerable amount of nitropicric acid. In order to ascertain, 
however, that the supposed nitropopulic acid was really what it appeared to be, a 
quantity of it was purified in the way already detailed, and subjected to analysis. 
0-2325 grm, of the acid, dried in vacuo, gave 0-314 CO 2 and 0-040 HO. 
Calculated numbers. Found numbers. 
C 36-84 36-81 
H 1-75 1-90 
Two quantities of the potash salt, prepared at different times, were also subjected 
to analysis. 
I. Prep. 0-2355 grm. salt gave 0-0378 KO 803 = 0-0421 KO=l7-45 per cent, 
11. Prep. 0-214 grm. salt gave 0-07 KO 803 = 0-0378 KO= 17-65 per cent. 
The calculated quantity of potash in the nitropopulate of that base is 17’70 per 
