144 Scientific Intelligence. [Fes. 
_the cylindrical vessel is to be opened, and so much air be permit- 
ted to enter by the minute aperture above-mentioned as shall 
be requisite to bring the two vessels in the same exact equilibrium 
as at the commencement of the experiment. The cylindrical 
vessel is then to be removed from the beam, and its stop-cock 
opened under mercury, and thus the precise bw/k of air contained 
in it be accurately measured, which bulk (if the whole vessel 
has been graduated to 1000 parts) represents the specific gravity 
of the gas weighed, common air being 1000. Thus, suppose 
hydrogen to be the subject of experiment, and it be found that 
69-44 parts of common air be equal in weight to 1000 parts of 
hydrogen, the specific gravity of hydrogen will be :06944 com~ 
mon air by 1:000, or itis 14-4 times lighter than common air. 
The above form of the apparatus is more particularly adapted 
for determining the specific gravity of gases fiaghteh than common 
air; but it is obvious that the principle upon which the method 
is founded is equally applicable to gases heavier than air, by a 
little modification in the apparatus. The advantages of the 
method are many and important. Besides the greater general 
accuracy attainable by measuring than weighing gases, the use 
of weights, as well as the necessity of ascertaining the bulk and 
weight of the apparatus, as inthe common mode of determinig 
the specific gravity of gases, are entirely superseded; nor are 
errors likely to arise from any change in the atmospheric temper- 
ature, or pressure, occurring during the performance of the 
experiment. 
II. Sulphate of Strontian. 
This substance has been lately found in considerable quantity 
at Carlisle, about 34 miles west of Albany, state of New York, 
imbedded in clay slate, forming very extensive strata. It was 
first tried by a common smith as a substitute for borax, and has 
been found the most useful flux ever employed in brazing and 
welding. By employimg a very small quantity of it in powder, 
instead of clay, he welded easily the most refractory steel; and 
im brazing, it proved superior to borax, on account of its remain- 
ing more fixed at a high temperature. 
Ill. Subterranean Noises. 
At Haddam, in Connecticut, for several years past, noises, 
like the firing of small arms, have been continually heard, which 
have been accompanied with almost continual concussions of 
the earth. So frequently have these effects been experienced, 
that they are quite disregarded by the inhabitants. About six 
years since, however, a serious explosion took place, which rent 
and dislocated large masses of the granite mountains. 
IV. Scientific Expedition in America. 
A scientific party will proceed in March to explore the natural 
productions of the numerous large rivers tributary to the Missis- 
