116 Scientific Intelligence. 
n a large amount of water, but, if the solution be nearly saturated, it 
shortly lets fall a of magnesia. In solutions of chlorid of ammo- 
nium and sulphate of ammonia, it is very slightly soluble, and is almost 
totally Gnsclubde 3 in solutions of-carbonate of ammonia. It is therefore 
inadmissible to employ carbonate of ammonia in ee eanete B pita 
of magnesia-ammonia, as Rose has pointed out in his Tra see 
Chem. Soc., May, 1862, p. 196 Rae 
11. On Arsenic in Sulphuric Acid.—Buoxam finds that all cine 
sulphuric acid contains a trace of arsenic which cannot be separated by 
boiling with hydrochloric acid, or chlorid of potassium, nor by repeat 
fractional distillation, either alone or with bichromate or permanganate of 
tash. 
Bloxam prepared pure sulphuric acid from sulphurous acid, steam, and 
nitric oxyd, but only when the sulpburous acid was oases from erystal- 
lized sulphite of soda and sulphuric acid at a low temperature, and ni- 
tric oxyd — nitre, sulphate of iron, and dilute eet acid at a very 
e 
Bloxam asia the arsenic of oil of vitriol to the sulphur, being able to 
detect it in the Sicilian sulphur employed in the manufacture of the 
purest s — n of commercial sulphuric acid.—Jour. Chem. “on - b 
1862, 
12. Eatnation of Lime-—Wicke converts oxalate of lime into 5 eulphats 
in the following manner: the dry oxalate is transferred toa platinum cru- 
cible, and the filter, after it is burned by itself, is added. The contents of 
e crucible are treated with such a quantity of pure’ concentrated sul- 
phuric acid that the mass is entirely saturated with it; great excess 
ing avoided. The crucible is now placed on the san bath until the ne 
— which consists in a moderate swelling of the mass and efferv 
cence, is over. Next, the excess of sulphuric acid is expelled by canticill 
heating over a small flame in a ventilating hood; finally, the residue 18 
—— ~— ~ sulphate of lime is weighed. Wicke found this method 
both ands —_- of execution.—Henneberg’s Journal fiir Land- 
wirtachay aan 
8. Quantitative suaacaaine of Starch—Starch has been pee 
hith echanical separation, a fermentation and weighing the 
bonie acid, re conversion into sugar and finding the amount of the iatie 
Of these methods none are worthy of entire confidence in the majority 
ee Fehling’s method, the best in most cases, has little value 
ally conducted, since the more delicate forms of cellulose pass int? 
by digestion with acids, while the insoluble albuminoids yield bo 
C “at with acids and diastase, substances which reduce alkaline 
copper solutions. 
Dr. Dragendorff of the Rostock Laboratory proceeds with starch detet 
minations as follows: the ete substance after drying out all hygro 
ic moisture at 212° is digested for 18-80 hours at a temperature . 
212° in 10-12 times its weight of a solution of 03 parts of hydrate 
potash in 94-95 parts of anhydrous alcohol. The digestion must 
~ place in ~— ass tubes, or in a silver vessel which admits of closing 
perfectly. treatment the albuminoid substances, the fats, the 
