38 SEVENTH REPORT—1837. 
to provide for the safety of the instruments, but also to allow of the ap- 
plication of a correction for any variation which they may undergo. 
Moreover, the method of experimenting on local temperature, proposed 
by M. Peltier, by using a thermo-multiplier, was applied by Mr, 
Forbes, and as far as a few observations could be relied on, the agree- 
ment of the two methods was remarkable ; but it was not thought pro- 
per to state the results of the experiments till they could be supported 
by one or more complete circles of observations. 
On a Method of constructing Magnets. By JAmMEs CUNNINGHAM. 
Having turned his attention to the construction of powerful magnets 
for electro-magnetic machines, the author tried steel of various quali- 
ties, but without satisfactory results. He finally tried cast iron, run 
into moulds of the required horse-shoe form, and found these highly 
carbonaceous masses remarkably retentive of magnetic power. 
On the possibility of effecting Telegraphic, or Signal Communications 
during Foggy Weather, and by Night in all Seasons. By Colonel 
C. Goxp. 
On an Instrument for Measuring the Electricity of the Atmosphere. By 
Lieutenant Morrison, R.N. 
CHEMISTRY. 
On the Products of the Decomposition of Uric Acid. By PRoFEssor 
Lizsic. 
“ The important part which uric acid performs in the animal economy 
has for a long time attracted the attention of the most distinguished 
physicians and chemists. Uric acid forms in one class of animals the 
whole of the excrement, and in another class it is its principal con- 
stituent, and it is accompanied by urea, a never-failing constituent of 
the human urine, Its extraordinary production in that morbid state 
of the body, which we call a predisposition of gout, is well known to 
give origin to one of the most painful diseases to which mankind is 
liable. It may be affirmed, with the utmost certainty, that urea and 
urie acids are products of the organization. We cannot discover their 
existence in any part of our food, nor do they constitute a part of any 
organ, as fibrin does of the blood, but they are chemical combinations 
