18 J. M. Ordway on Nitrates. as 
" 
The trihydrate melts at 238°. It has been cooled down to 
i 338°. 
. 
and was not absolutely free from didymium and cerium. 
Be 
too 
asic. “ But the addition of strong nitric acid, induced a rapid | 
crystallization, the temperature rising to 142 
When the salt was boiled not quite so long, the product could a 
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same effect on the melting point as dilution with water. 
TETRAHYDRATES, 
Nitrate of Strontia, & 8,—Unlike any other hydrated ni- 
trate, this salt crystallizes in the monometric system 
e composition of hydrated nitrate of strontia is always laid — 
down in the books as 8 NH;. But this formula has no analogy — 
_ In its favor, and having repeatedly tried good erystals formed at — 
a low temperature I have invariably found but four equivalents _ 
of water. The nitrate crystallized above 75° F., is generally 
» anhydrous, and that formed below 60° is hydrated, but between 
these temperatures there is no certainty. ‘Thus a solution satu- — 
rated at 84° F., while cooling down to 62°, deposited nothing 
but anhydrous crystals; and a solution saturated at 71°, by 
standing some hours where the thermometer did not get below 
70°, gave only fully hydrated crystals. , 
The hydrated salt is resolved by heat into a liquid and the 
anhydrous nitrate. Even the hot weather of summer causes it 
to sweat, if kept in a close vessel. In dry air, it loses all its 
water by efflorescence. 
Nitrate of Lime, Oa & H,.—Melts at 111° F, Some that was 
heated only to 124°, . to crystallize when it had cooled to 
96°. After being heated to 153°, it remained liquid over night © 
and got down to 574°. This salt boils at 270°. ‘When the boil- - 
ing 1s continued, the mass remains liquid and clear till about one 
third of the water passes off. Farther heating renders it anhy- 
drous, with scarcely any loss of acid. This dry residue evolves — 
a strong heat in recombining with water. 
See 
2 
ee 
Slatin 
