10 HISTORY OF CHEMISTRY. [LECTURE I. 



we must consider, in a general way at least, the chemical know- 

 ledge and labours of the phlogistians. 



Their chemistry consisted especially of a rather incomplete 

 knowledge of the chemical and physical properties of a series 

 of substances which occur in nature. They had learned how 

 to prepare other substances from these, and their endeavours 

 were directed to the discovery and recognition of new sub- 

 stances. Hence we find an already remarkable development 

 of qualitative analysis, which we owe chiefly to Bergman, 

 whilst quantitative methods were almost wholly unknown. 

 Naturally, the theoretical bases did not permit of any value 

 being attached to chemical proportions by weight. 



In order to give a general idea of the substances known at 

 that time I shall mention some of them. Sulphur, charcoal, 

 gold, silver, copper, iron, tin, and lead were certainly known 

 to the most ancient peoples ; the discovery of mercury belongs 

 to the Greek period ; that of antimony, bismuth, and zinc to ' 

 the middle ages ; that of arsenic, phosphorus, cobalt, nickel, 

 platinum, etc., to the period of phlogiston. Scheele, who was 

 the most fertile discoverer amongst the phlogistians, discovered 

 manganese and chlorine. The metallic calces, or oxides, as we 

 should say, were looked upon as different by all the chemists 

 of the period ; yet Macquer thought this difference might be 

 referred to the more or less incomplete expulsion of the phlo- 

 giston, and he therefore assumed the existence of the same 

 earthy constituent in all the metals. 10 Amongst those earths 

 which were not classed with the metallic calces, they knew 

 lime, alumina, and magnesia. Scheele discovered baryta. 

 They divided the alkalies into the caustic and the mild 

 (carbonated), the latter being regarded as substances which 

 might pass into the former by taking up fire material. Potashes 

 were in use from the ^ailiest times ; the Arabians probably 

 made known the preparation of caustic potash from potashes and 

 lime ; nitre was also known, and served for the manufacture of 

 gunpowder. Soda or potash had been already employed by 



10 Kopp, Geschichte. 3, 143. 



