ial eel Be i 
in photometrical observations, screens should be used which 
are not very smooth, and the shadows should be brought 
near each other ; ‘and even so = to allow their borders to 
touch. —Ferrusac’s Bull. Oct. 1827. 
32. Im urity of rain. water.—In eae thirty ounces 
of rain water every month, which at the end of the an 
amounted to: three hundred and sixty ounces, M. Bran 
obtained a-total residuum of 2.75 grains. It was com me 
of resin, pyrrhin, (a vegeto-animal substance,) mucus, hydro- 
chlorate, sulphate and carbonate of magnesia, hy lo- 
rate of soda, sulphate and carbonate of lime, hydro-chlorate 
of potash, oxide of iron and manganese, and an ammoniacal 
id. 
salt.— 
33. Sulphur in vom sim —In reer assafcetida with 
caustic potash, and adding an acid to the solution, efferves- 
cence is produced, anda gas disengaged ileal colors paper 
of acetate of lead like shipharetted hydrogen. 
alcoholic solution of assafcetida be evaporated, and 
the residuum be treated with aqua regia, a liquid is eee 
which contains sulphuric acid. - 
oe burning the volatile ‘ol of aséafettida in a pure state, a 
strong odor of sulphurous acid is This oil, 
heated to redness with potash, ogo a mixture of chase 
coal and sulphuret of potash. M. Zeise presumes that his 
ulterior researches will enable os to icin r sulphur in a 
great number of organic substan t may be remember- 
ed also that M. Planche has already ‘detected the presence of 
suiphar:s in the umbellifera.—Jbi 
34. Incompatible salts—M. Brandes has demonstrated 
b means of an artificial mineral water, that the waters of 
has 
bonate of lime; because if these latter salts co-exist, even 
in a large quantity of water, a material decomposition takes 
place. e.—Ibid. 
35. Steam Engines. in Great Britain.—It is confidently 
asserted that there are now in Great Britain, fifteen thousand 
steamyengines. Some of them are of prodigious size. In 
the county of Cornwall for nag? there are some of the 
Vor. XV.—No. 
