1870.] Chemistry. 399 



obtained from snow, care being taken to prevent the loss or decom- 

 position of the peroxide alluded to. The author's opinion is that, 

 since the experiments made at Kasan undoubtedly proved the pre- 

 sence of the peroxide of hydrogen in snow-water, there may exist 

 an essential difference, caused by the locality where it falls. Kasan 

 is situated almost in the centre of the Kussian empire, far away 

 from any seas or oceans. 



On the other hand, Professor H. Struve has ascertained the 

 presence of peroxide of hydrogen in air. His chief results are, (1) 

 peroxide of hydrogen is formed in air simultaneously with ozone 

 and nitrate of ammonia, and is condensed in the rain-water; (2) 

 peroxide of hydrogen, ozone, and nitrate of ammonia, are intimately 

 connected together; (3) the change which the so-called ozone- 

 paper undergoes when exposed to air is due to the joint action of 

 ozone and peroxide of hydrogen; (4) peroxide of hydrogen does 

 not decompose solution of iodide of potassium with separation of 

 free iodine ; (5) free carbonic acid decomposes the solution of iodide 

 of potassium, causing the formation of carbonate of potassa and free 

 hydriodic acid ; (6) when the peroxide of hydrogen is present along 

 with carbonic acid (acting as just alluded to), iodine is separated ; 

 (7) the best and most effective reagent for the detection of small 

 traces of peroxide of hydrogen is oxide of lead, since puce-coloured 

 peroxide is formed. 



According to J. Jouglet, nitro-glycerine, dynamite, iodide of 

 nitrogen, chloride of nitrogen, and some other similar compounds, 

 explode the very moment they are brought into contact with ozone ; 

 so that, for instance, a drop of nitro-glycerine, introduced into a 

 vessel containing ozone, causes an instantaneous explosion. Picrate 

 of potassa gunpowder, and ordinary gunpowder, are slowly decom- 

 posed by ozone, a decomposition which, as regards the last-named 

 substance, takes several weeks before it is perceptible. 



Under the name of Albolith, Dr. Eiemann prepares a cement 

 chiefly consisting of magnesia For this purpose, the magnesite of 

 Frankenstein (Silesia) is ignited in retorts similar to those used for 

 gas-manufacture; and after the mineral (a. native carbonate of 

 magnesia) has been ignited, it is mixed with silica and some other 

 substances. This mixture has the property of yielding, with mode- 

 rately concentrated solutions of chlorides (for instance, chloride of 

 magnesium), an extremely plastic, but, on drying, a very hard 

 material, excellently adapted for use as cement for stucco and or- 

 namental work, and instead of gypsum. 



In a research on Isinglass, J. L. Souberain states that the dif- 

 ferent varieties of this article, as met with in the trade, may be 

 recognized as follows : — Russian isinglass dissolves rapidly and in- 

 stantaneously in hot water, leaving hardly ever more than at most 

 2 per cent, insoluble residue; Bengal isinglass dissolves readily, 



