136 TRANSACTIONS OF THE [Fres. 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 employed in the process. The retorts, as well 
as other articles had been supplied 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 apparatus 
for generating oxygen was a simple retort, to the neck of which 
he 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. 
Watt 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 pamphlet states that this apparatus 
are especially adapted for procuring *‘hydrocarbonate and 
oxygen air.”’ 
Meanwhile, across the Channel, in Paris, the opulent physi- 
cist and chemist, the unfortunate Lavoisier, enjoyed the 
advantages of highly specialized and admirably constructed 
apparatus of every description. An inspection of the plates in 
the Traité élémentaire de chimie’’ (1798) shows what a wealth of 
excellent utensils he had at his command. Two sketches by 
