Experiments on various Eartlis, 15Q 



the original experiment a de-oxidation had taken place, 

 and that by the reassumption of oxygen the present effect 

 had been produced. 



I then thought of pursuing some mode of operation which 

 would enable me to detect what proportions of oxygen were 

 united to the various earths. This I thought of accom- 

 plishing by a set of comparative experiments in the fusing 

 of pure malleable iron with the different earths. Iron being 

 a highly oxidable metal, the quantities disappearing would 

 indicate the comparative quantities of oxygen in each of the 

 earths. This was with a view to form the most ample data 

 for subsequent experiments, and to compare the alkalis 

 with alkaline earths. These experiments embraced a 

 number of substances, as will be brought forward in the 

 t'tMail. 



T, — 200 grains of calcareous earth (very pure Paris white), 

 deprived of its carbonic acid, were mixed with 50 grains of 

 iron filings : these were mixed together and exposed to a 

 high decree of heat ; a perfect fusion of the earth had taken 

 place, which was now converted into a black glass of a deep 

 jetty lustre. Two small but finely polished spherules of 

 metal were obtained weighing 12 grains — loss by oxidation 

 38 grains, or 76* per cent. It may be proper to state here, 

 that SO grains of malleable iron filings, ihe same used in 

 this and the following experiments, were fused for ie in ten 

 minutes, and the button formed in consequence weighed 

 4 7' grains— loss onlv 74- percent. — oxidation in consequence 

 of the calcareous earth nearly 70 per cent. more. 



f J.— 100 grains of pure barytes and .50 grains of ri}ini>s of. 

 malleable iron were fused together. - A black brownish 

 opaque irlass was obtained, and beneath a smooth-skinned 

 metallic spherule was found weighingl)' grains — loss 40 1 

 grains— equal to 81 per cent. L'mrn the portion of the earth 

 to the iron in this experiment being double, in place of 

 quadruple, as in cite last experiment, it was inferred that 100 

 q rains of calcareous earth would oxidate 19 grains of irotf, 

 whereas 100 grains of 'barytes in Una experiment oxidated 

 41 j grains. 



III.— 100 



