SCIENTIFIC SUMMARY. 
425 
are not to be disputed, but the real question is, — will it pay to overcome 
them? And this question may possibly before long be answered in the 
affirmative. 
Dr. F. Crace Calvert has been making some experiments on the action 
of sulphuric acid on lead, from which it appears that pure lead is much 
more rapidly attacked by the acid than that containing small quantities 
of other metals, and in fact so small a quantity as 04 per cent, of tin 
contained in lead diminishes the action of the acid about one-third ; a 
point of some importance to sulphuric acid manufacturers. 
Drs. Lawes and Gilbert have for upwards of twenty years been making ex- 
periments on the assimilation of nitrogen by plants ; their last results have 
reference to the question whether plants possess the power of assimilating 
free nitrogen. The method of procedure was to enclose the plant in a glass 
vessel and to supply it with a current of air which had been washed with 
sulphuric acid and with carbonate of soda ; the soil employed had been pre- 
viously ignited and allowed to cool over sulphuric acid ; carbonic acid was 
occasionally supplied with the air that passed through the apparatus. 
The seeds that were allowed to germinate under these circumstances 
showed a singular power of prolonging their vitality ; one part feeding on 
the nitrogenous matter set free by the decay of another part, but in no 
instance was there found to be an increase in the amount of combined 
nitrogen beyond that originally contained in the seed. 
Two deaths have lately occurred from the inhalation of the vapour of 
nitric acid. A bottle containing the acid having been broken and the 
contents spilt on the floor, the fumes acted on the lungs of the two persons 
present to such an extent that, although they felt no immediate ill effects, 
they both died, one within about ten hours and the other within two days 
after the occurrence. This serious accident should serve as a caution to 
chemists, and others who are liable to be exposed to acid fumes. 
M. Crova has succeeded in producing artificially the compound of 
acetylene and copper, which is found in the interior of copper tubes which 
have been employed for the conveyance of coal gas, and which possesses 
the property of detonating by a blow, or by a slight elevation of tem- 
perature. The mode of proceeding was to expose finely divided copper to 
the action of a mixture of equal volumes of air and acetylene ; the 
absorption of gas appears to be greater if a little ammonia were present. 
The very rare metal rubidium has been found to exist in a situation 
where few would perhaps anticipate its presence, namely, in ordinary 
beetroot; the raw beetroot salt has been found to contain from OT 3 to 
0 - 21 per cent, of chloride of rubidium. 
The equivalents of the two metals nickel and cobalt have lately been 
determined with great accuracy by Dr. W. .T. Russel. He adopted the 
precaution of igniting the oxide of cobalt, employed for the determination 
of the equivalent, in a blowpipe flame, and of cooling it out of contact 
with the air, by which a definite protoxide was obtained ; the oxide was 
then reduced by hydrogen. The equivalent of cobalt determined in this 
manner proved to be 29'37, and that of nickel, determined by a perfectly 
similar process, was found to be 29‘369 ; the coincidence between the two 
equivalents being very striking. 
