344 
be, plunged, each, into the vessel below it, 
when the crystals will fall off, and the spe- 
cimens are again to be suspended as be- 
fore. This process is to be repeated, every 
time the erystals form on the specimen. 
The trial should be concluded at the end 
of the fifth day, after the appearance of the 
first crystals; and if the stone, brick, or 
mortar under trial, be capable of resisting 
the frost, the salt will remove nothing from 
it, neither in grains, nor scales, nor frag- 
ments; and the solution which was placed 
beneath it will remain pure. Where two 
stones are to be subjected to a comparative 
trial, the specimens must be weighed before 
the trial, and the matter separated from 
each must be collected, washed, dried and 
weighed; and the relative loss of weight 
indicates the proportion which the speci- 
mens tried would suffer, by exposure to 
the weather and frost. 
_ The Moisture absorbed by different Kinds 
of Paper, in an atmosphere saturated with 
moisture, has been determined by Mr. 
Griffiths. Known weights of the different 
specimens dried well by the fire, were ex- 
posed to air saturated with damp, for 
24 hours, when they were found to have 
increased the following increase of weight, 
in 100 parts— 
Foolscap Paper ......... 18-2. 
Wartridep sects cetuascacees 
BLOWN cc cserscecsapnssnncs 
ENGI® op ccccocscdpoancceedes : 
Filtering ......... seasedien ) Us 
Quarterly Journal of Science. 
Similar experiments were made by Count 
Rumford. on the materials used for cloth- 
ing ; but a more extended series would be 
desirable, and we hope Mr. Griffiths will 
find leisure to pursue the inquiry, he has 
begun with so much care. 
Various measurements have been made 
of the Heights of Mont Blanc and Mont 
Rosa, and after a very elaborate examina- 
tion of these measurements, M. De Wel- 
den gives the following as the results, 
which appear to be most accurate :— 
Toises. English Feet. 
Mont Blane...2,46 ... or...15,737 
Mont Rosa ...2,3703... or ...15,157 
Margosa Oil, which is obtained by ex- 
pression from the nut or seed of the Mar- 
gosa tree, at Madras, is said to have some 
valuable medicinal properties, besides being 
useful as a preservative of perishable sub- 
‘stances of various kinds. The natives rub 
their holays or cadjores with it. On these their 
vedas, histories, &c. are written ; and those 
of upwards of two centuries and a half old 
were nearly as fresh and in as good con- 
dition as those recently taken from the 
tree. Mr. Allsop thinks this oil might be 
used with advantage to preserve cables, 
cordage, canvas, leather, &c. from the at- 
tacks of worms, or other vermin; and that 
it would be useful to apply to shelves, sides 
Spirit of Philosophical Discovery. 
[May I, 
&e. of book-cases, trunks, and the like.— 
Tech. Rep. 
Faraday’s Tubes for the Preservation of 
small Quantities of expensive Fluids for Che- 
mical Experiments. —A_ piece of glass tube, 
of a quarter of an inch or more in diameter, 
being selected, it is to be closed, at one end, 
by the blow-pipe ; and then, being softened 
near the other end, it is to be drawn out 
obliquely, so as to form a narrow tapering 
neck, with a short piece ofthe tube attached 
to serve as a funnel for introducing the 
fluid which is to be preserved. Put the 
fluid into the funnel, and then warm the 
body of the tube, by which the air it con- 
tains will be expanded, and part passes out 
through the liquid ; and as soon as the tube 
is again cooled the liquid descends into it, 
and a spirit-lamp being applied to the taper- 
ing part of the neck, softens the glass, so 
that it may be drawn out to a fine point 
and hermetically sealed. In this state the 
fluid may be kept clean and pure for any 
length of time; and tubes of this kind are 
easily labelled, by writing the name of the 
substance with a diamond upon the glass. 
When a portion of the fluid is wanted, 
pinch off the extreme point of the neck, 
and incline the tube till the proper quan- 
tity has entered the neck, then warm the 
tube with the hand till the air within it 
expands, and pushes out the quanity re- 
quired; and the neck may be sealed again 
as perfectly as before.—Quarterly Journal 
of Science. 
There is less uniformity in the Tempera- 
ture of Fluids at the Boiling Point than is 
generally supposed. From the experi- 
ments of Dr. Bostock, it appears that a 
variation of 50° may be produced in the 
temperature of the boiling point of ether, 
and from 4° to 5° in that of water, by add- 
ing extraneous matters, the atmospheric 
pressure being the same. The liquids 
boiled at a lower temperature when copper 
filings were added, and still lower by add- 
ing fragments of glass; but the lowest 
point of ebullition was obtained by intro- 
ducing thin chips of cedar wood.—Annals 
of Philosophy. 
Human Hair retains its hygrometrie pro- 
perty for an immense length of time. M. 
Pictet has lately compared recent human 
hair with that from the head of a mummy 
from the Isle of Teneriffe, and found that 
two hygrometers, one constructed with 
each kind of hair, were equally sensible. 
The object of the experiment. was to: esta- 
blish the constancy of those properties 
which render hair valuable as a hygrome- 
tric substance. The interval, between the 
extremes of moisture and dryness, was 
passed in three minutes, in both instru- 
ments. 
Method: of the Least Squares.—The mode 
of determining the co-efficients of a given 
function, by means. of what are called Equa- 
tions 
