D. CHEMISTRY AND METALLURGY. 213 



ton of acid. It may be assumed, therefore, that to produce 

 an acid of 66 Baume (containing 94 per cent, of real acid), 

 there is a loss to the still per ton of acid of one gramme when 

 nitrous compounds are absent, and of 2^ to 3 grammes when 

 they are present. If, however, the concentration be carried 

 above 66, these numbers are much increased. In a still 

 weicrhincr 30 kiloGrrammes, 180 tons of acid, containing 97 to 

 98 per cent, of real acid, were produced. The still lost 1092 

 grammes of platinum, or 6.07 grammes per ton of acid. In 

 producing 47i tons of acid of 99|- per cent., there was a loss 

 of 8.8 grammes of platinum per ton of acid, and an analysis 

 of the acid showed that it contained 8.38 grammes of pla- 

 tinum to the ton, present in it in solution, thus proving the 

 loss to be a chemical one. To the figures here given for the 

 loss of the body of the retort, about 13 per cent, should be 

 added for the loss of the other parts. The use of a plati- 

 num-iridium alloy for the stills prevents to a large extent this 

 action, but the brittleness and consequent fragility of the 

 alloy is a serious objection to it. Bull. jSoc. 6Vi,,II., xxiv., 

 i:>ec., 1875,501. 



NON-OXIDATION OF CARBONIC OXIDE BY OZONE. 



The question of valency among the elements is a funda- 

 mental one in chemistry; and while all chemists are agreed 

 that a given atom may form a series of compounds with the 

 same substance, they are divided on the question of the in- 

 terpretation of this phenomenon. On the one hand, it is 

 claimed that the valence of an atom is fixed and invariable, 

 and consequently all but one of its compounds, and that the 

 highest, must be unsaturated. On the other, it is asserted 

 that the valence is variable, and that by twos, and conse- 

 quently that in the lower of two compounds formed by an 

 element it is as fully saturated as in the higher. Carbonic 

 oxide, for instance, whose molecule contains one carbon and 

 one oxygen atom, has, according to the former view, two free 

 bonds. But according to the latter it is saturated, though 

 at a lower stage than in carbon dioxide. The weak point in 

 the theory of variable valence is the law of, or the cause for, 

 the variation. The constitution of carbonic oxide being thus 

 in doubt, Remsen and Southworth have sought to throw 

 some light upon it by acting upon it with ozone, a body 



