1819.] Scientific Writings of Dr, Ingenhousz. 87 
10. Some further Considerations on the Influence of the Vege- 
table Kingdom on the Animal Creation. Phil. Trans. 1782, p. 
426.—Our author’s opinion that vegetables emit oxygen gas 
when growing in the sun, and that the injury done to the air by 
the breathmg of animals and by combustion is in this way 
repaired, having been called in question by some persons, and 
at having been alleged that it was altogether refuted in Dr. 
Priestley’s fifth volume of experiments on air, Dr. Ingenhousz 
made a public exhibition of the most decisive of his former 
experiments to a number of his scientific friends. He boiled 
pump water for two hours to deprive it of its air. It was then 
put into glass vessels placed inverted over mercury, to shut out 
the communication with the atmosphere. Some conferva rivu- 
laris was put into two of these glasses, some pieces of cloth 
into other two, and nothing in other two. The first two glasses 
began in three days to yield oxygen gas, which on examination 
proved very pure, and the conferva gave out altogether about 
eight times its bulk of this gas. In 10 days, it ceased to vege- 
tate, and began to decay. ‘The cloth gave out no air whatever; 
neither was any air collected in the jars into which nothing had 
been put even at the end of some months. A glass containing 
pump water unboiled began to yield air much sooner, and it 
yielded a greater quantity ; but it was not so pure. 
11. Nouvelles een et Observations sur divers Objets de 
Physique. A Paris, 1785.—This is chiefly a French translation 
of the papers of Dr. Ingenhousz, already printed in the Phil. 
Trans. He was induced, he tells us in the preface, to translate 
them himself, because all the translations which he had seen 
contained mistakes which materiaily altered his meaning. In 
his own translation, he was enabled to rectify these mistakes ; 
and he likewise added some additional illustrations, which he 
thought likely still further to elucidate the subject. It will enly 
be necessary, therefore, to notice the papers which made their 
first appearance in this octavo volume of 498 pages. 
The first paper is an outline of the Franklinian theory of 
electnicity ; very short; but clear and precise ; and exhibited 
without any mathematical phraseology. In this respect, he 
followed the example of Dr. Franklin himself. 
The second paper is a theory of the electrophorus, more 
detailed than the paper on the same subject in the Transactions, 
but quite the same in point of theory. 
The third paper is of some length, and consists of a set 
of observations on a question at that time agitated with great 
keenness in England ; whether thunder rods ought to terminate 
in points, or round knobs. ‘The question had originated in the 
gunpowder magazine at Purfleet having been struck with 
lightning. A committee of the Royal Society had been 
appointed to investigate the subject. From the report of this 
committee, Mr. Wilson dissented. He affirmed that the extre- 
