Ld 
TRANSACTIONS OF SECTION B. 769 
- Sometimes this principle is heavy and sometimes it is not; sometimes it is free 
fire and sometimes it is fire combined with the earthy element ; sometimes it passes 
through the pores of vessels and sometimes they are impenetrable to it: it explains 
at once causticity and non-causticity, transparency and opacity, colours and the 
absence of colours. It is a veritable Proteus which changes its form every 
moment.’ 
But Lavoisier had merely renounced one fetich for another. At the time that 
he penned these lines he was as much under the thraldom of le principe oxygine as 
the most devoted follower of Stahl was in the bondage of phlogiston, The idea 
thatthe calcination of metals was but a slow combustion had been fully recognised. 
-“M. Berthelot tells us that as far back as the March of 1774 Lavoisier had written in 
“his laboratory journal : ‘I am persuaded that the inflammation of inflammable air 
is nothing but a fixation of a portion of the atmospheric air, a decomposition of 
air... . In that case in every inflammation of air there ought to be an increase 
of weight,’ and he tried to ascertain this by burning hydrogen at the mouth of ,a 
vessel from which it was being disengaged. In the following year he asks, what 
remains when inflammable air is burnt completely? According to the theory by 
which he is now swayed it should be an acid, and he made many attempts to cap- 
_ ture this acid. In1777 he and Bucquet burnt six pints of the inflammable air from 
- metals in a bottle containing lime-water, in the expectation that fixed air would be 
_ the result. And in 1781 he repeated the experiment with Gengembre, with the 
- modification that the oxygen was caused to burn in an atmosphere of hydrogen, but 
not a trace of any acid product could be detected. Of course there must have been 
considerable quantities of water formed in these experiments, but Lavoisier was 
preoccupied with the conviction that oxidation meant acidification, and its presence 
was unnoticed, or, if noticed, was unheeded. Macquer, in 1776, had drawn atten- 
tion to the formation of water during the combustion of hydrogen in air, but 
Lavoisier has stated that he was ignorant of that observation. What was it, then, 
that put him on the right track? We venture to think that M. Berthelot has him- 
self supplied the answer. He says (p. 114): ‘ Rumours of Cavendish’s trials had 
spread throughout the scientific world during the spring of 1783. . . . Lavoisier, 
always on the alert as to the nature of the products of the combustion of hydrogen, 
was now in such position that the slightest hint would enable him to comprehend 
its true nature. He hastened to repeat his trials, as he had the right to do, never 
having ceased to occupy himself with a question which lay at the very heart of his 
doctrine.’ 
‘On the 24th of June, 1783,’ continues M. Berthelot, ‘he repeated the com- 
bustion of hydrogen in oxygen, and he obtained a notable quantity of water 
without any other product, and he concluded from the conditions under which he 
had worked that the weight of the water formed could not be other than equal to 
that of the two gases which had formed it. The experiment was made in the 
presence of several men of science, among whom was Blagden, a member of the 
Royal Society of London, who on this occasion recalled the observations of 
Cavendish (qui rappela a cette occasion les observations de Cavendish). 
On the following day Lavoisier published his results. The following is the 
official minute of the communication taken from the register of the sittings of the 
Académie des Sciences :— 
Meeting of Wednesday, June 25, 1783. 
R MM, Lavoisier and De Laplace announced that they had lately repeated the com- 
_bustion of Combustible Air with Dephlogisticated Air; they worked with about 60 pints 
of the airs, and the combustion was made in a closed vessel: the result was very pure 
water. 
————— =. OU 
__ The cautious scribe who penned that minute did not commit himself too far. 
M. Berthelot, however, regards it as the first certain date of publication, esta- 
Dblished by authentic documents, in the history of the discovery of the composition 
of water; ‘a discovery,’ he adds, ‘ which, on account of its importance, has excited 
the keenest discussion.’ 
You will search in vain through the laboratory journals, as given by M. 
