Scientific Intelligence. — Arts. 199 
which arises from the formation of an iodide of starch. M. de 
Ballard, after improving the means of operating with this re- 
agent, announces his having discovered iodine in bodies which 
were not hitherto known to possess it, for example, in various 
marine mollusca, both naked and testaceous, such as the animals 
of the genera Doris , Venus, Ostrea, &c., several Polyparia and 
marine vegetables, Gorgonia, Zoster a marina, & c., and, in parti- 
cular, in the brine of salt-works fed by the Mediterranean. The 
very small quantity of iodine found in the water of the sea has 
prevented his determining in what state it exists, but there is 
reason to suppose that it is in the state of hydriodate. — Annales 
de Chim. et de Phys., Fev. 1825. 
ARTS. 
26. Improved Cement for holding small Lenses , whilst grind- 
ing and polishing them . — In grinding small lenses, Mr Prit- 
chard found that shell-lac, the cement usually employed for them, 
was by no means sufficiently strong to retain them. He was 
fortunate enough, however, to attain his object by adding to the 
shell-lac an equal weight of finely levigated pumice, carefully 
melting them together in an iron- vessel, and stirring them till 
well incorporated. Great care is required in using it, not to 
heat it hotter than is absolutely required in melting it, and in 
fixing the lens securely, otherwise it becomes unfit for use ; and 
the same caution is equally required in using shell-lac alone. 
POLITICAL ECONOMY. 
27. Present Population of Ireland, as contrasted with that of 
other Countries. — The returns for Ireland in 1821 are, 
Males, - - 3,341,926 
Females, - - 3,459,901 
Total, 6,801,829 
This, taking the surface of Ireland at 18,700 Irish square miles* 
gives 363 persons to an Irish square mile. The density of this 
population is evinced by the following comparison : 
Ireland, 
England, 
Scotland, 
Wales, 
France, 
Confederated States of Germany, 
223 " 
207 
70 
98 ' 
144 
111 
to an English Square mile. 
