1819.] Scientific Writings of Dr. Ingenhousz. : 89 
In the fifteenth paper he gives us an account of some attempts 
to make artificial magnets atter the manner of Dr. Gowan Knight; 
but these attempts were not very successful. 
In the sixteenth paper, he gives his theory of gunpowder. He 
expatiates at greater length; but the theory is precisely the 
same as that which he had already given in the Transactions. 
The seventeenth paper isan application of the same theory to 
fulminating powder. 
The eighteenth paperis one of the most valuable in this volume. 
It consists in a set of experiments made to determine which of 
the seven metals, gold, silver, copper, tin, steel, iron, and lead, 
conducted heat best. The mode of making the experiment was 
contrived by Dr. Franklin, who hkewise supplied the materials. 
Wires of each of these metals of the same length and thickness 
were coated with wax, and their ends dipped into boiling water. 
The wire on which the wax was melted and highest up was 
reckoned the best conductor. Silver was found the best con- 
ductor, and lead the worst in all the experiments. Copper was 
the next best conductor, gold the next best, tin, steel, and iron, 
next best. 
In the last paper contained in this volume, Dr. Ingenhousz 
describes his mode of burning iron wire in oxygen gas, and his 
attempts to burn the other metals in the same gas. These last 
attempts, except with platinum wire, had not been successful. 
These are the only writings of Dr. Ingenhousz which | have 
had the opportunity of perusing. They contain, I believe, all 
the additions of any importance which he made to chemistry 
or electricity. His turn of mind did not lead him so much to 
the investigation of the properties of bodies as to the discovery 
of what he considered to be striking or brilliant; and having 
got something of this kind, he seems often to have remained 
satisfied without any attempt to investigate what actually hap- 
pened during the experiment. Thus the analysis of the combus- 
tion of iron wire in oxygen, and of the vapour of ether in 
oxygen, he left to Lavoisier and Cruikshanks, who, by investi- 
gating them with care, established important theoretical poimts 
_ in the science of chemistry, and thus contributed materially to 
improve it. 
ARTICLE II. 
Contributions towards the History of Anthraxothionic Acid, disco- 
vered by Porrett, and called by him Sulphuretted Chyaxic 
Acid. By Theodor von Grotthuss. 
(Concluded from p. 50.) 
Sect. 17.—By this stochiometrical analysis, we find the pro- 
portion of water in the copper anthrazothionhydrate determined 
