i i 2 Salt Ammoniac . 
above, there is formed a Kind of Zigzag, 
with Spiculet like thofe in the other Figures, 
as at 7. 
To obtain the Crjflals of this Salt, his 
neceifary to place a Drop of a frefh Solution 
(made in warm Water) before the Micro- 
fcope, without giving it any other Heat 
than the Warmth of the Water. The re¬ 
gular Cryftals will then appear as reprefent* 
ed at the Side of the Drop A, B, C. The 
laft of which Figures C is produced from 
the fecond B, by new Formations at each 
Corner of the crofs Branches, when the 
whole Procefs is nearly ended : but thefe 
Cryilals are rarely feen, unlefs the Solution 
be examined as foon as made. 
Salt Ammoniac is particularly remarkable 
for rendering Water wherein it is diflplved 
colder than ,any other Salt can do, and even 
equal in Degree to Water that is near freez¬ 
ing. Monfieur Geoffroy placed a common 
Thermometer of eighteen Inches long; in a 
Phial wherein he had put a Pint of Water, 
and let it remain therein a fufficient Time 
to adjufl; itfelf to the Temperature of the 
Water: he then put into the Water four 
Ounces of Salt Ammoniac , and in lefs than a 
Quarter of an Hour the Liquor in the 
Thermometer defc.ended two Inches, and 
nine Lines. He then tried the fame Expe¬ 
riment with Salt-Petre inflead of Salt Am¬ 
moniac, ufing the like Precautions, and the 
_ - '_- . Liquor 
