164 Scientific Intelligence. 
Other experiments have given 1 in 71 feet. ‘The observations are 
affected by the varying conductivity of the rocks, and by the percolation 
of water. The author has exhibited upon a diagram, in which the ordi- 
nates are depths, and the abscisse temperatures, the results obtained 
between the depths of 231 and 717 yards. The strata of the mine are 
also shown in section, Additional to these, the author gave a table of 
similar results in another pit at the same colliery, taken between the depths 
of 1673 and 467 yards, and showing an increase of temperature of 1° in 
106 feet of descent. Assuming as an hypothesis, that the law thus found 
for a depth of 790 yards, continues to operate at greater depths, we 
arrive at the conclusion that at 24 miles from the surface a temperature 
of 212° would be reached, and at forty miles a temperature of 3000°, 
which we may suppose sufficient to melt the hardest rocks. The author 
then discusses the effect of pressure and increased conductivity of the 
rocks in modifying this result. If the fusing point increased 1°°3 F. for 
every 500 lbs. pressure, as is the case with wax, spermaceti, &c., the depth 
would be increased from 40 to 65 miles before the fluid nucleus would be 
reached; but as the same increase is not observed with tin and barytes, 
the influence of pressure on the thickness of the crust cannot yet be deter- 
mined. Again, Mr Hopkins has shown that the conductivity of the dense 
igneous rocks is twice as great as that of the superficial sedimentary 
deposits of clay, sand, chalk, &e. And these close-grained igneous rocks 
are those which we believe must most resemble the strata at great depths. 
Now, if the conductivity of the lower rocks be twice as great as that of 
the strata in which the observations were made, correcting our former 
estimate, we should probably have to descend 80 or 100 miles, instead of 
40, to reach a temperature of 3,000°, besides the further increase due to 
the influence of pressure on the fusing point. On entirely independent 
data, Mr Hopkins has been led to conclude that the minimum thickness of 
the crust does not fall short of 800 miles, in which case the superficial tem- 
perature of the crust would have to be accounted for from some other cause 
than an internal fluid nucleus.—Proc. Lit. and Phil. Soc. Manchester. 
MISCELLANEOUS. 
On the Alleged Practice of Arsenic Eating in Styria, By Dr H. E. 
Roscor.—Dr Roscoe being anxious to obtain further definite information 
respecting the extraordinary statements of Von Tschudi, quoted by 
Johnston in his ‘‘ Chemistry of Common Life,” that persons in Styria 
are in the habit of regularly taking doses of arsenious acid, varying in 
quantity from 2 to 5 grains daily, was supplied, through the kindness of 
his friend Professor Pebal, of Lemberg, with a series of letters written 
by seventeen medical men of Styria, to the Government medical inspector 
at Gratz, concerning the alleged practice. After reviewing the opinions 
of Dr Taylor, Mr Kesteven, and Mr Heisch, upon the subject, and having | 
mentioned the results and conclusions arrived at by those who had pre- 
viously interested themselves with the subject, Mr Roscoe stated that all 
the letters received from the medical men in Styria, agree in acknow- 
ledging the general prevalence of a belief, that certain persons are in 
the habit of continually taking arsenic in quantities usually supposed 
sufficient to produce death. Many of the reporting medical men had no 
experience of the practice ; others describe certain cases of arsenic eating, 
which have not come under their personal notice, but which they have 
been told of by trustworthy people whose names are given ; whilst others, 
again, report upon cases which they themselves have observed. Pro- 
fessor Roscoe proceeded to bring forward, in the first place, evidence 
bearing upon the question,—Is, or is not, arsenious acid, or arsenic in 
any other form, well known to, and distributed amongst the people of 
Styria? He said that he had received 6 grms. of a white substance, for- 
