1835] BecquereVs Traite Experimental, Sfc. 75 



elements of air, would produce at first, protoxide of azote ; then 

 nitrate of ammonia, which when decomposed, resolves itself into 

 protoxide of azote and vapour of water. The nitrate acts upon the 

 alkaline carbonates and forms nitrate of potash, while the ammonia 

 is disengaged in union with carbonic acid. He applies his theory to 

 explain the production of nitrate of ammonia, dissolved in rain by the 

 electric agency. He concludes by observing, that in every electric 

 chemical action, however feeble it may be, if water is decomposed in 

 contact with air, ammonia is formed. 



Last geological revolution. — Becquerel endeavours to calculate 

 this period, by a method which it must be allowed is extremely 

 vague. He finds that the cathedral of Limoges, which has stood for 

 four centuries, and is built of granite, is decomposed on that side 

 where the winds and the rain beat to the depth of 3J lines, and that 

 the rock in situ is disintegrated to the depth of 5 feet or 720 lines. 

 If both have progressed at the same rate, he conceives that the rock 

 in its natural place must have been decomposing for above 82,000 

 years. 



Terrestrial magnetism. — From the facts which have been 

 brought forward by Humboldt and others, it appears proper, that 

 experiments should be made upon the magnetism of the rocks, which 

 constitute the formations of the country in which the experimenter is 

 placed, or at least to determine at what point the extent of oscilla- 

 tions diminishes without changing their number. 



Atmospheric electricity. — Saussure has shewn that in summer 

 the electricity of the calm air is much weaker than in winter ; and 

 that the apparent force of electricity, depends not so much on the 

 absolute height of the place of observation as upon the relative 

 height, or on the insulation of the place. Disseminated as this prin- 

 ciple is through the medium of the vapour of water, it is highly 

 probable that it exercises no inconsiderable effect on the plants and 

 animals which are of necessity subjected to its influence. 



Becquerel terminates the first volume of his work, with some 

 remarks upon the agencies by which the decomposition of some rocks 

 and the formation of some insoluble compounds may be explained, 

 which comprehends a recapitulation of some points. But he shews 

 more particularly, how electro-chemical action operates in producing 

 many minerals. Phosphate of iron in mines and crevices he con- 

 siders to be the result of the action of electricity, which is disengaged 

 during the peroxidation of iron and the decomposition of organic 

 matter. The formation of the chromate of lead as it exists native, 

 may be imitated by treating a solution of nitrate of lead with chalk 

 and then with chromate of potash. In the course of a montli or two, 

 crystals of chromate of lead were observed on the surface of the 

 chalk. By mixing sub-nitrate of copper, with arseniate of copper, 

 a double arseniate of copper and ammonia, and of arseniate of lime and 

 ammonia is formed. The re-action of bi-carbonate of soda upon 

 gypsum gives origin to carbonate of lime which crystallizes, sul- 

 phate of soda remaining in solution. 



A supplementary chapter is appended, containing a short outline 

 of the interesting electro- chemical researches of Dr. Faraday. 



