Chemistry and Physics. 147 
watch glass. In the open air at the Rothamsted farm, nitrous acid 
was detected by this air test. In six days the reaction appeared 
in water exposed to this air, and in twenty-seven days it con- 
tained one part of nitrogen in 15,000,000. es rain water the 
ae dia test readily shows nitrous acid, except when the 
rains are exceptionally heavy.—/. Chem. Soc., xxxix, 229, May, 
881. Gs oR: 
n Boron hydride.—Jones and Taytor have examined 
are the ed es and properties of the boron hydride 
discovered by the former in 1879, Three methods of preparing 
boric oxide, finely powdered, upon magnesium dust; 2d, the 
direct union of magnesium and boron; and 3d, the "action of 
magnesium on boron trichloride. Though the two latter methods 
magnesium boride is placed “h a flask with a little water and 
gas which has an extremely di disagreeable and characteristic rae 
producing nausea and headache, is slightly soluble in water, ich 
ugh a solution of silver nitrate giving a black precipi- 
tate Senin boron and silver, and is — to sie acid 
by potassium permanganate solution. With ammonia t gavea 
compouisa decomposed by acids. On analysis the ehoron apace 
to be combined with 2°86 parts ey confirming the — 
BH,.—J. Chem. Soc., xxxix, 213, Ma 1. 
the Purification of Carbon Disul liphi ide. So hcieee ey as a 
osed ph de. hi es oe and uareaare raves of purifying carbon 
ide 
ad e 
tated after e nell addition, the process being stopped when the | 
reduction of the eannsanite is no longer produced, and the 
s, the 
rant in is obtained free from water a & means of a sepa rating 
5. . Boborie Abeonpt on of Crystals.—Professor H. A. Tasriend 
and Mr, E. H. ites discuss the — whether there should 
be electric abso please in a_ perfectly ae le medium. 
The theory indicates that there should be none, and the writers 
have tested the point by experiment, and it, ‘was found that 
Iceland spar had no electric absorption. This substance can be 
