me 
1322. ] 
milk, but this effect is only temporary ; 
for not being soluble, they gradually sub- 
side. The high price of sugar, were there 
no other consideration, precludes its use. 
The lactometer differs but little in form 
from the common hydrometer. Its dis- 
tinction is to be found in its seale, which is 
adapted to skimmed milk. It is made of 
brass, and consists of a pear-shaped bulb, 
at the top of which is a graduated stem, 
and at the bottom a brass wire to the end 
of whicha weight is screwed. The scale 
begins about three-fourths of an inch from 
the bottom of the stem, and is marked 0, 
which corresponds with the specific gravity 
of the lightest genuine skimmed milk, or 
1-035, distilled water being 1:000. The 
dots and figures which extend from 0 to 
39, indicate “ parts of water in 100 paris 
skimmed milk at 60°,” as is engraved on 
the reverse of the stem, and has been as- 
certained by experiment. The instrument 
is constructed for the temperature of 
63° of Fahr., a point judged the most con- 
venient, as it agrees very nearly with the 
temperature of the milk brought to our 
markets during the summer. As all fluids 
expand by heat aud contract by cold, in 
using the lactometer an allowance must be 
made of 1o on the instrument for every 
3° of temperature, that the wilk under 
examination is either above or below 600 of 
Fabr. Thus the lactometer, which would 
remain at 0 in milk of the temperature of 
609, would sink lo below’ 0, if the tem- 
perature of the milk were increased to 
63°; 20 if it were raised to 669, &c. And 
on the contrary, if the temperature of the 
same milk were reduced to 579, the instru- 
ment would then experience a rise above 
0 equalto 1o,&c. This lactometeris made 
by Mr. Bennett, mathematical instrument 
maker, Cork, and sold in a tin case, either 
with or without a small thermometer. It 
is scarcely necessary to give directions 
for using so simple an instrument. All 
that is required, is, to fill the tin case with 
the milk to be examined, immerse the lac- 
tometer in the milk, and observe the point 
at which it remains stationary after it rises. 
Note also the temperature of the milk, and 
if necessary, make the allowance directed 
for expansion or contraction of volume. 
The Prussian Stale Gazette mentions a 
discovery which Dr.SeEBECK had com- 
muunicated to the Academy of Sciences, at 
Berlin, in three different sittings. It was 
* on the magnetic properties iherent in all 
metals and many earths (and not in iron 
alone as was supposed,) according to the 
difference of the deyrees of heat. 
At Pavia, new trials have been made, 
which prove the efficacy of oxygenated 
muriatic acid in subduing the hydropho- 
bia. Dr. Previsali had prescribed it with 
success where the symptoms were ad- 
vasced, in a liquid form, from a drachm 
Report of Chemistry and Experimental Philosophy. 
63 
to a drachm and a half daily, in citron 
water or syrup of citron, 
Mr. CHARLES CAMERON, Glasgow, has 
published in Dr. Brewster’s Journal a de- 
scription of a new method of forming cru- 
cibles. The Dutch have long enjoyed an 
almost exclusive monopoly in ithe manufac- 
ture of the small melting-pot, or clay cru- 
cible, used by the jeweller and silversmith. 
I established a small manufactory of them, 
as follows: for each of the different sizes 
of the crucibles, I formed ten or twelve 
dozen of moulds of stueco, burnt and pow- 
dered in the usual manner. For the first 
mould of each size, [ formed a piece of 
soft pipe clay into the shape of the intend- 
ed crucible, and laid it with its mouth 
downwards on a flat surface, and inclosed 
it with a cylinder of white-iron, distant 
about half an inch from the angular poin.s 
of the crucible, and about an inch and a 
half higher than its bottom: then mixing 
the stucco with water, poured it into the 
cylinder. When the stucco was suffici- 
ently set, | removed the white-iron, picked 
out the clay, and dried the mould: I then 
squeezed sott clay into the mould, which 
on standing a few minutes, easily came out 
again. It was inclosed in the cylinder, 
and stucco poured round it, which formed 
a second mould, continuing to do so until 
I had procured the nuniber wanted. They 
were then all put into a stove, and com- 
pletely dried ready for use. - In the prepa- 
ration of the fire-clay for the crucibles, I 
followed precisely the same process used 
at the potteries, by mixing it with a very 
large quantity of water, and putting the 
whole through a No. 9 silk searce. On 
allowing the whole to stand a few hours, 
the clay subsided, and in pouring off the 
clear water, I procured the clay or slip of 
the consistence of thick cream. On weigh- 
ing a gallon of it, I fuund the proportion of 
clay it contained, and added sand to the 
whole, in the proportion of seven of sand 
to seventeen of clay; I then stirred and 
mixed the whole completely, when it was 
ready for use. I next took my moulds, 
previously dried, and arranged them in 
parallel rows on a table, and successively 
filled them with the prepared slip. By 
the time I had filled four or five dozen, [ 
returned to the one first filled, and began 
alternately to pour the slip out of them, 
leaving a small quantity unpoured out, 
which subsided, and gave the requisite 
thickness to the bottom. In each of the 
moulds so filled, a crucible is completely 
formed by the abstraction of the water of 
the slip, in contact with, and adjoining to, 
the porous substance of the stucco mould. 
The crucible will be either thicker or 
thinner in proportion to the time the slip 
has remained init. Five or six dozen will 
not require more than fifteen minutes in 
being formed. The moulds with their con- 
tents 
