Chemistry and Physics. 231 



ance. There is a possibility, not only of accidental contamina- 

 tion, but of wilful adulteration. The best means for testing 

 radium preparations for raesothorium is to remove the radium 

 emanation either by heating or by solution and evaporation ; 

 then the presence of y-rays after a few hours shows the presence 

 of mesothorium. The proportion of y-rays before and after this 

 treatment gives an indication of the amounts of the two radio- 

 active substances present. — JSerichte, xliii, 3420. h. l. w. 



2. The Combustion of Hydrocarbons. — In a recent lecture 

 before the British Association, W. A. Bone has given a review 

 of the present knowledge of gaseous combustion, much of which 

 is due to his own important researches. The opinion which 

 formerly prevailed among chemists that in combustion the hydro- 

 gen of hydrocarbons is first attacked by oxygen with the forma- 

 tion of steam is incorrect. It has been known for a long time 

 that when ethylene and acetylene are exploded with equal vol- 

 umes of oxygen, carbon monoxide and hydrogen are practically 

 the only products, as follows : 



C 3 H 4 + 2 = 2CO + 2H a 

 C,H a + O s = 2CO+ H 2 



Bone has shown that the oxidation of the hydrocarbons at com- 

 paratively low temperatures proceeds by addition of oxygen 

 to the molecule and the successive formation of hydroxyl prod- 

 ucts — alcohols, aldehydes, formic acid and finally carbonic acid. 

 It appears that combustion at higher temperatures goes on in 

 the same way, and it has been found that oxygen has a much 

 greater affinity for the hydrocarbons than for hydrogen and car- 

 bon monoxide. For example, when detonating gas is exploded 

 with acetylene in the proportion C 2 H 2 -t-2H 2 + 2 , there is abso- 

 lutely no separation of carbon nor formation of steam, and practi- 

 cally the same thing holds good in the case of a mixture of 

 ethylene, hydrogen and oxygen corresponding to C 2 H 4 + H 2 + 2 . 

 In the presence of a hydrocarbon, carbon monoxide is attacked 

 by oxygen even less readily than is hydrogen. These observations 

 have an important bearing on the chemistry of flames. Hitherto 

 hydrogen has been considered as one of the most combustible of 

 gases, but in reality it is very much less so than the hydrocarbons. 

 It is probably not so much th eoriginal hydrocarbon as its hydrox- 

 ylated molecule which decomposes in ordinary flames, and experi- 

 mental evidence does not warrant the view, so often encountered 

 in scientific literature, that hydrocarbons are resolved into their 

 elements prior to being burnt. — Chem. JSfews, cii, 309. h. l. w. 



3. Supposed Chemical Distinction between Orthoclase and 

 Microcline. — Two or three years ago the view was advanced by 

 Barbier that orthoclase differs from microcline in the fact that 

 the former contains traces of lithium and rubidium, while these 

 elements are not found in the latter. It appears, however, that 

 Ramage had previously found these alkali metals in a microcline 

 from Dalkley in Ireland, and that Vernadsky, somewhat later, 



