ABUSE OF HYPOTHESES IS A SOURCE OF ERROR. 135 



we might ; or, by combining it in an illogical manner, we 

 infer what is wrong. The best remedy for these defects is 

 a training in logic and mathematics applied to science 



Partially disciplined workers in science often draw 

 conclusions which are not proved by the evidence ; and 

 even experienced investigators, when carried away by en- 

 thusiasm in their occupation, occasionally make the same 

 mistake, and fancy they have made a new discovery when 

 they have really committed an error. In this way begin- 

 ners in science and others have frequently mistaken both 

 the peroxide and mineral sulphide of iron for metallic 

 gold, magnetic oxide of iron in tea for iron-filings, a pre- 

 cipitate of the mixed oxides of iron and aluminium for the 

 oxide of a new metal, &c. Before knowledge of science 

 also had sufficiently advanced, even experienced chemists 

 mistook the earths silica and alumina for the same sub- 

 stance ; similarly with baryta and strontia, sulphur and sele- 

 nium, sodium and potassium, also caesium and potassium, 

 &c. And under the influence of scientific enthusiasm many 

 supposed discoveries of new elementary substances have at 

 different periods been made. More than forty such in- 

 stances have occurred since the year 1770, and the follow- 

 ing is a list of them : Tobern Bergmann,in 1777, extracted 

 from diamonds what he considered to be a new earth, and 

 called it 'terra nobilis.' Meyer, in 1780, discovered 'hy- 

 drosiderum ' by dissolving cast-iron in acids; and Klaproth 

 afterwards proved it to be a phosphide of iron. Monnet, 

 in 1784, discovered what he called 'saturnum.' Klaproth 

 also, in 1788, discovered ' diamond-spatherde ' in corun- 

 dum. Wedgwood, in 1 7 90, discovered f australia ' in sand 

 obtained from the continent of that name ; but Hatchett 

 proved it to be merely a mixture of silica, alumina, oxide 

 of iron, and plumbago. In 1799 Fernandes supposed that 

 he had discovered a new earth. Hahnemann discovered 



