236 Scientific Intelligence. (Serr. 
gravity indicated by Mohs is 3°5, while that of the jeffersonite has, in 
every instance which Ihave seen, exceeded this limit. 
« The chemical analysis offers another important difference, in the 
absence of magnesia, which appears to be essential to pyroxene. 
_ For these and other reasons, I conceive that there canbe no doubt 
as to the necessity of considering this mineral as a distinct species. I 
am inclined to believe that a closer study of the diopside and fassaite, 
and of the pyroxene analogique, might lead to their separation from the 
pyroxene and union with the jeffersonite. This is a subject which 
appears to me fraught with interest, but upon which I am not able to 
offer any thing but conjectures, as my specimens of these minerals are 
not as good as would be necessary to enable me to decide this point. 
I shall close these remarks merely by observing that a similar opinion 
is, I believe, entertained by Mr, Vanuxem.” 
IV. Instrument for measuring the Compression of Water. 
Prof. Oersted has used a very simple instrument for measuring the 
compression of water. He fills a cylinder of glass with water which 
has been deprived of its air, the cylinder has on its upper end an air- 
tight cover of brass, through which a screw passes with a small piston 
of brass on its lower end, which presses on the water. In the cylinder, 
is a thermometer tube filled with the same water as the cylinder, and 
having on its upper open end a small column of mercury which, the 
tube being very narrow, remains there without sinking into the bulb. 
Suppose now the water being pressed in the cylinder by screwing down 
the piston, this pressure will act equally powerful on the open end of the 
tube, as on the outsidé. of the bulb, so that the pressure being equal on 
the interior and on: the,exterior side of the glass bulb, neither expan- 
sion nor contraction of:its walls can take place, the state of the mercury 
above the water in the glass tube will, therefore, immediately indicate 
the compression. Professor Oersted had previously ascertained the 
capacity of the bulb and of the tube by weighing the mercury which 
they were able to hold. The pressure exerted by the screw on the 
water was measured by another tube filled with air, likewise inclosed in 
the cylinder. Thus he obtained the result, that the compressibility of 
water diminishes very quickly with the increase of pressure, and that 
the mean compressibility at a pressure of 3 to 4 atmospheres is 
45°0 
1000000 
ments of Canton. 
for each atmosphere, which agrees pretty well with the experi- 
V. Tutenag. 
This substance has lately been analyzed by Dr. Fyfe. The follow- 
ing is the Doctor’s account of the specimen he examined : 
*¢ Dr. Howison, of Lanarkshire, was so fortunate, when in China, as 
to procure a basin and ewer of Chinese or white copper, a part of which 
he sent me for analysis. From the experiments I have performed on 
it, I find the composition to be different from what is stated by the 
above-named chemists, its component parts being copper, zinc, nickel, 
and iron; the last of which, however, is but in small quantity. 
“The basin in the possession of Dr. Howison is of a whitish colour, 
approaching to that of silver, and is very sonorous. When held in one 
hand, and struck with the fingers of the other, the sound is distinetly 
heard at the distance of an English mile. It is also highly polished, 
q 
" 
h 
— Ss 
