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POPULAR SClENCIi REVIEW. 
600 ft. in granite, quartz, talc, and marble, with one drill-head, the diamond- 
points show no wear. 
The Heating Poicer of Mineral Oils was the subject of a memoir lately 
read before the French Academy, by M. Deville. He experimented on 
petroleum and other mineral oils in large numbers. The mineral oil was 
submitted to distillation in a copper alembic furnished with a long serpent 
tube, and also with a thermometer. By means of this apparatus, the amount 
of distillate passing over at various temperatures was estimated. The danger 
possible by explosion was measured by the proportion distilling below 140°. 
The same experimental fact represents as well the loss which must be 
sustained to remove the explosive property of the oil. Another danger is 
encountered when the oils are enclosed in airtight vessels— explo.d on by 
dilation. The amount of space necessary to be left above a mineral oil is 
calculated from the coefficient of dilation. The data M. Deville has obtained 
from each sample are drawn, generally, from the following determinations : — 
Loss by heating to 100°, to 120°, and so on, by intervals of 20° up to 200° ; 
this is expressed in percentages ; composition of the oil — percentages of 
carbon, hydrogen, and oxygen, obtained by combustion ; density at zero, 
and at 50°, and coefficient of dilation ; composition and density of the oil 
obtained by distillation, and density of the residue. In some cases the 
specific heat has been determined, and the latent heat at the mean 
temperature. M. Deville’s memoir contained tables giving an immense 
number of experimental results. 
The Science of Alloys . — In a recent lecture before the Royal Institution, 
Dr. Matthiessen, F.R.S., of St. Mary’s Hospital, gave an interesting 
summary of the researches conducted by himself and other physicists on this 
important subject. After demonstrating, by means of a most ingeniously 
contrived apparatus, that the electrical and heat-conducting powers of the 
alloys follow the same curves, he stated that the analogy between the 
relation existing in this case and in some others may be shown experimentally, 
as follows: — When bars of alloys and their component metals are struck, a 
great difference will be found in the note produced ; and in almost every case 
where the experiment has been made, the most sonorous alloy was found to 
correspond in composition, approximately, with that at the turning-point of 
the electric conducting-power curve.. When wires of the same diameter of 
metals and alloys are broken by traction, those of the allojs will require a 
much greater force than their component metals; and it may be deduced, 
from what is known, that those alloys the composition of which cor- 
responds to the turning-point of the conducting-power curve are more 
tenacious than any other alloy composed of the same metals. When 
spirals of wires of metals and their alloys are weighted to an equal extent, 
the alloys will be found, on removing the weights, to possess the property 
of resuming their original form in a much higher degree than their com- 
ponent metals. Here again the allo3^s corresponding in compo-sition to those 
of the turning-point of the conducting-power curves are the most elastic. 
From what has been said, and from the experiments described, the con- 
clusion may be drawn that the chemical composition of the practically-used 
two-metal alloj^s corre.sponds to those situated at the tuining-pomts of the 
heat and electric conducting-power curves, and that if a two-metal alloy 
