i 9 6 SCIENTIFIC APPARATUS. 



in the art of metallurgy. Besides gold and silver, copper (or 

 brass), iron, tin, and lead are mentioned in the books of Moses, 

 whereas during the Trojan war, some considerable time after 

 Moses, Homer states that swords of bronze were still in use. 



Pliny, in his Natural History, written in the first century, 

 describes very carefully many chemical substances, the processes 

 by which they are obtained, and their applications in the arts ; 

 treating of the metals, painters' colours, glass, dyeing, calico- 

 printing, soap, starch, beer, stone-ware, and precious stones. His 

 writings are characterized by accuracy, and indicate persevering 

 research. Nevertheless, his statements are sometimes incom- 

 plete, which is no doubt due to the fact that in his time a study 

 of the arts was considered to be below the notice of philosophers 

 and others in high station, a failing which has perhaps not 

 entirely disappeared from the society of the present day. Pliny 

 mentions mercury as being well known in his time. 



Chemistry was much advanced by the Arabians, who devoted a 

 great deal of attention to the preparation of chemical medicines. 

 They mixed various substances together and submitted the mix- 

 tures to the action of heat. In this way many new bodies were 

 formed; and we find that Geber, in the eighth century, was 

 acquainted with the processes of distillation and filtration, with 

 the use of the water-bath, with the mode of purifying common 

 salt. He knew the carbonates of potash and soda, the nitrates of 

 potash and soda, nitric acid, nitrate of silver, sal ammoniac, aqua 

 regia and its power of dissolving gold, alum, sulphuric acid, 

 copperas, borax, distilled vinegar, corrosive sublimate, oxide of 

 mercury, milk of sulphur, several metallic sulphides, arsenic, and 

 white arsenic, and the oxides of copper and iron. He considered 

 the metals to be compounds of mercury and sulphur of various 

 qualities and in different quantities, and it was this belief which 

 made him think it possible by proper processes to convert the 

 metals into one another, thus constituting him the first alchemist. 



The influence of the Arabians on chemistry is evidenced by 



