OXALATES, NITRATES, PHOSPHATES, SULPHATES, AND CHLORIDES. 61 
It appears from the second of these experiments that the subnitrate of bismuth 
may be produced at a temperature so low as 180° Fahr., and from the first experi- 
ment that the subnitrate may be exposed to a temperature of 500° Fahr. without de- 
composition. 
Several experiments were made to produce another definite subnitrate, containing 
a greater proportion of oxide of bismuth, by the action of heat upon this subnitrate, 
but without success. The salt was partially decomposed at various temperatures 
under redness, but no definite compound resulted. Hence the subnitrate described 
is probably the only definite subnitrate of bismuth that can exist. The small pearly 
crystals obtained on throwing the neutral nitrate of bismuth into a moderate quan- 
tity of water, are of the same composition as the subnitrate obtained by heat. 
5. Nitrate of Zinc. 
Zn N H 3 + 3 H. 
This salt is easily obtained by dissolving zinc in nitric acid. It is very soluble in 
water, and moderately deliquescent. 
Experiment. 29* 1 7 grains of the crystals ignited, left 7'86 grains oxide of zinc. In 
this experiment we have 0-2694 oxide from one salt, which is very near 0-2713 oxide, 
the proportion which should be left, supposing the salt to contain six atoms of water. 
By efflorescence at 212° one part of this salt loses 0-18 water, which is one half of the 
whole water which the salt is assumed to contain, namely, 0‘3639 water. It loses 
no acid at 212°. Hence tills salt is of the same constitution as the nitrate of copper, 
but is not decomposed at so low a temperature. The proportion of water, however, 
cannot be reduced below three atoms without a loss of acid, and there appears to be 
a subnitrate of zinc resembling the subnitrate of copper. 
6. Nitrate of Magnesia. 
MgN H 3 + 3 H. 
Experiment. 27' 12 grains of crystals of nitrate of magnesia, when calcined, left 
4*3 grains caustic magnesia; a result which indicates 6-17 atomic proportions of 
water in the salt, or the salt contains six atoms of water. 
The nitrate of magnesia stands exposure to a heat which would melt lead without 
losing acid. At that high temperature the proportion of water is reduced to one 
atom, which cannot be expelled without loss of acid. The salt remains in a fused 
state and transparent, and dissolves afterwards completely in water. 
Experiment. 18-40 grains of the crystals, containing- 7*7 1 grains water, lost 6’60 
grains by a strong sand-bath heat continued till the salt ceased to lose weight. This 
is a loss of exactly five sixths of the water contained in the salt. 
Experiment. 1976 grains, containing 8*28 water, by similar treatment lost 677, 
