136 TRANSACTIONS OF THE [FeB. 27 



a basis for damages. This inventory has been preserved and 

 affords detailed knowledge of the material resources of the 

 chemists of the period. It is divided into groups, philosophical 

 instruments, electrical, optical, mathematical and chemical 

 apparatus, with a small stock of substances, the whole footing 

 up to the value of £605. The imperfections of some of the 

 apparatus used by Priestley are shown by the fact that he 

 experimented from December, 1782, to May, 1783, on the direct 

 conversion of water into air by distillation only without the 

 intervention of any other substance, to discover after all that 

 this astonishing result was due solely to leaks in the porous 

 earthen retorts emi^loyed in the process. The retorts, as well 

 as other articles had been sui^plied gratis by Joseph Wedgwood; 

 and Priestley, writing for more, desired to have them glazed 

 within and without. (Scientific Correspondence of Priestley. 

 New York, 1892.) 



Scheele, the poor apothecary in a little village of remote 

 Sweden, had to contend with obstacles sufficient to crush any 

 but the bravest heart. With a few bottles, bladders, common 

 dishes, and the simple appliances of a primitive pharmacy, this 

 man of expedients accomplished wonders. Scheele's api^aratus 

 for generating oxygen was a simple retort, to the neck of which 

 be tied a bladder. He was not acquainted with the pneumatic 

 trough at the time of his chief discoveries. (Scheele's " Air 

 and Fire," London, 1780.) 



In 1796 James Watt, the English engineer, published an 

 account of a simplified " Pneumatic Apparatus for Preparing 

 Factitious Airs." In this is figured an "air-holder'' made of 

 tin-plate japanned inside and out, into which gas is conducted 

 from the generating retort in a furnace, by means of a metallic 

 tube bent at an angle of 45°, and terminating in the air-holder. 

 AVatt lays great stress on the advantages of inclining the 

 "lower pipe," as stated, through Hales certainly anticipated 

 him in this point. This pneumatic apparatus was manufactured 

 by Boulton and Watt, at Soho, in two forms ; a large size sold 

 for £10 2s. 6d, including auxiliary articles, and a portable 

 apparatus for £3 15s. The pam^Dhlet states that this apparatus 

 ai'e especiall}^ adaj^ted for procuring • ' hydrocarbonate and 

 oxygen air." 



Meanwhile, across the Channel, in Paris, the 02:)ulent jihysi- 

 cist and chemist, the unfortvmate Lavoisier, enjoyed the 

 advantages of highly specialized and admirably constructed 

 ajiparatus of every description. An inspection of the plates in 

 the Traite elemenlaire de chimie" (1798) shows what a wealth of 

 excellent utensils he had at his command. Two sketches by 



