662 
DR. A. MATTHIESSEN AND MR. a. C. FOSTER ON 
Calculated. 
Found. 
c 8 h 7 o 4 . . . 
. . 167 
60-73 
— 
Ag .... 
. . 108 
39-27 
39-15 
C 8 H 7 Ag0 4 . 
. . 275 
100-00 
The properties of this acid are given in our former communication (p. 358). 
When methyl-hypogallic acid is treated with dilute nitric acid (1 part acid to 3 parts 
water) and gently heated till the acid is dissolved, it is converted into a nitro-acid which 
separates out on cooling. Its composition was found to be 
C 8 H 6 N 2 0 8 =C 8 H 6 (N0 2 ) 2 0 4 . 
I. 0-5760 grm. gave 0-7850 carbonic acid and 0T216 grm. water. 
II. A nitrogen determination made by Liebig’s method gave the ratio of carbonic 
acid to nitrogen as 8 ’07 to 1. 
Calculated. Found. 
f 
-'1 
, -A- 
C 8 . . . . 
. 96 
37-21 
I. 
37-17 
II. 
H 6 . . . . 
6 
2-33 
2-35 
— 
N 2 . . . . 
. 28 
10-85 
— 
10-74 
0 8 . . . . 
. 128 
49-61 
— 
— 
c 8 h 6 n 2 o 8 . 
. 258 
100-00 
This acid may be called dinitromethyl-hypogallic acid, as it contains (N 0 2 ) 2 in place 
of H 2 . 
It crystallizes with one molecule of water. 
2T33 grms. of the crystallized acid lost at 100° C. 0T38 grm. water. 
Calculated. Found. 
C 8 H 6 N 2 0 8 . . . . 258 A 93-48 
H 2 0 18 6-52 6-47 
C 8 H 6 N 2 0 8 , H 2 0 . 276 100-00 
4. On the different crystalline Forms of Hemijpinic Acid. 
Whilst experimenting with hemipinic acid we found that this acid may crystallize in 
different forms. The crystals were found to contain different amounts of water ; thus 
(I.) when crystallized from a dilute solution by spontaneous evaporation, the crystals 
contain half a molecule of water ; (II.) when from a supersaturated solution, they contain 
one molecule; and lastly, (HI.) when crystallized in the ordinary way by cooling a hot 
solution, they contain two molecules. 
I. 11-281 grms. acid lost at 100° C. 0-448 grm. water. 
II. 3-130 grms. acid lost at 100° C. 0-230 grm. water. 
III. 7-646 grms. acid lost at 100° C. 1-0576 grm. water. 
