150 Scientific Intelligence. 



In comparing such analyses, to determine the practical value 

 of a given water for soda making, the relation of the amount 

 of sulphate to the total amount of carbonate is of the greatest 

 importance, since the greater the relative amount of sulphate, 

 the more difficult it will be to obtain a high grade carbonate by 

 simple solar evaporation. If this relative amount is small, a 

 large excess of chlorides may be present without materially 

 complicating the process. The relation between the mono- 

 carbonate and the bicarbonate should, for best results, be a 

 molecule of each plus an excess of monocarbonate. The 

 amount of necessary excess is not yet accurately determined 

 but is probably under a molecule. Judged by this standard, 

 the water of Abert Lake is the best, Ragtown the worst, of 

 those here considered, while Owen's Lake, occupying a middle 

 position as regards purity, is, owing to its geographical position 

 and climatic environment, probably the one best adapted for 

 practical utilization. 



SCIENTIFIC INTELLIGENCE. 4^ 



y 



I. Chemistry and Physics. O* 



1. On the Molecular weight of Nitrogen peroxide. — Vapor 

 density methods appear incapable of establishing definitely the 

 molecular constitution of nitrogen peroxide, although rendering 

 it probable that at low temperatures this substance is represented 

 by the formula N 2 G 4 . Ramsay has therefore applied to this ques- 

 tion a method founded upon the researches of Raoult, which have 

 proved that the depression of the freezing point of a liquid caused 

 by the presence of dissolved liquid or solid is proportional to the 

 absolute amount of substance dissolved and inversely proportional 

 to its molecular weight. Raoult found the law to hold almost 

 universally, the exceptions being very few. Thus using glacial 

 acetic acid as the solvent, he found that out of 150 substances 

 examined, scarcely half a dozen gave abnormal results. Ram- 

 say's apparatus consisted of a wide test tube closed with a rubber 

 cork, having two holes, through one of which a thermometer 

 passes and through the other a glass tube in which plays a stirrer. 

 The apparatus is placed in a beaker, and by adding hot or cold 

 water, its temperature may be raised above or depressed below 

 the freezing point of the solvent. In a first experiment 41*02 

 grams of glacial acetic acid were weighed into the apparatus, its 

 melting point being 16 •680°. A small bulb of nitrogen peroxide, 

 containing 0*378 gram, was then broken in the acetic acid by 

 means of the stirrer, and the melting point again observed. It 

 was found to be 16*300°, having been lowered 0*380°. Hence one 

 per cent of the peroxide would have lowered the melting point 



