114 sf Stienific Intelligence: 
-eplone disappears and the fluid becomes colorless. - re addition of fsbo 
of sulphate of ammonia, removes the remaining hyponitric acid ; 
of the hydrochloric acid has been removed by the site and anphele 
‘ous and arsenous acids carried to their highest stage of oxydation. 
The o oxyds present, aid the further purification ; by continuing the con- 
centration to 1°78, a trifling addition of oxyd of lead is made, but it . 
essential to the success of the process oe this point of density be 
reached. e fluid mustsnow be coole eep vessels of lead, thie 
temperature of it being gradually reduced to. 32° and allo eed 
become perfectly clear. The clear part must then be run into shallow 
lead vessels so placed that they may be refrigerated to 0 Fabr. As the 
whole acid has nearly the hydrate composition of S0,-+-2HO, it would 
form by repose a solid crystalline mass. In ordinary cases, the regular 
crystals form solid masses, which are allowed to increase, till one ~hal 
. 
as is rapidly removed, the crystals broken up and. ee with 
acid desalltie from the crystals of a former operatio ee 
rhe erystallized in this way, nearly all the ‘coment which 
can be detected, arises from the fine granular sediment of anhydrous — 
washed with sarsioniy sui hine acid, afford an kala ele 
if required in the concentrated state, may be pines swe to 
the platinum alembic, melted and boiled. For the ate 
‘searches, the crystals must be melted in glass, or or neler a, 
tallized out of contact with metals or dust, leaving oetale fserart | , 
of the acid in a fluid state. If the subsequent use of the acid does not 
require the remoyal of the water, which is very rarely the case, the 
crystals being a perfectly definite hydrate when fluid, best us Bg 
weigh and apportion the wane of real acid with great pre 
n the laboratory, when used for cases of difficult decomposition i 
may be added to the eystaliaed bisulphate of potash, mix ie 
substance to be acted on, and the whole brought to any oe of dty- , 
ness in the platinum utensils employed in such « operations, | 
All the acid from which the pure acid has been abstracted, may be © 
sed for generating One or hyponitric acid in the manufacture of 
snlphoric acid. The manufacture may best be carried on ie Ld : 
winter months, and a aes obtained, stored, or melted. 
crystals. ‘They are oblique four sided prisms, and often present faces .° 
of twelve by sixteen inches. Their capacity for heat is also sage te 
small parcels paperes at the mean temperature of 46° F., pirat ’ 
extreme slown 
Lowell, oui Apiit 28th, 1848. 
ape 
