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FOPULA.R SCIENCE REVIEW. 
from four to ten times the strength of common powder, and is stronger 
than dynamite. 
The Preparation of Artificial Porphyry. — It is stated that MM. Sepulchre 
and Ohresser have perfectly succeeded in utilising the slag of the iron blast 
furnaces for the manufacture of paving stones, which withstand a crushing 
weight of more than 400 kilos, per square centimetre, and have answered 
for the purpose of paving several streets at Brussels and Paris, and stood 
heavy traffic far better than even the celebrated Quenast stones. The streets 
paved with this material at Brussels have a heavy gradient. 
Graphite in Ceylon. — According to the statements lately made in some of 
the Ceylon papers, it would seem that there is a large abundance of plum- 
bago in that island. The following quotation is what we refer to : — Fresh 
discoveries of the mineral are constantly made. Should mining continue at 
the rate of the past few years, government will have to regulate the pursuit 
with reference to the safety of the people, otherwise lives will be lost from 
foul air and the collapse of badly-formed pits. We observe that the Cham- 
ber of Commerce found the specimens of this mineral sent some time ago 
from Hambantette to be defective from the presence of “rust,” or, as the 
natives call it, 11 water mark.” The progress of this staple export has been 
from 46,000 ewt. to, in round numbers, 200,000. The quantity has consider- 
ably more than quadrupled in five years, and more than doubled in the past 
as compared with the previous season. 
The Recently Discovered Coal in India . — The Mining Journal says that the 
question as to the precise character of the mineral discovered in the Kistnah 
district is at present attracting considerable attention, and it has received 
from Colonel F. Applegath, of Vizanagram (who, it will be remembered, 
found and burnt coal at Jaggiapetta some years ago), a small specimen of 
the fuel, which may be examined at its office by those interested. The 
specimen forwarded is too small to permit of a decided opinion being formed 
respecting it, but Dr. Benjamin H. Paul, F.C.S., to whom the editor has 
submitted it, and who has long devoted special attention to the examination 
of fuels, states that it appears to possess all the characteristics ot a lignite or 
brown coal. From the fact mentioned, that the sample is taken from near 
the outcrop, he considers it would not be possible to judge with certainty of 
the quality of the mineral as fuel, though it is probable it would prove very 
valuable in this respect, especially in India. 
Discovery of an Ancient Silver Mine . — The recent earthquakes in Germany 
have caused the fall of a large mass of rocks situated between Heidelberg 
and Wiesloch, and in consequence thereof the works of a silver mine, worked 
by the ancient Romans, have bee.i brought to light. There is no silver-ore 
of any importance left, but, instead, a very rich zinc ore is met with in large 
quantity, which was left untouched by the former workers. 
The Examination of Alloys. — In a paper published in the American Jour- 
nal of Science for January, Mr. F. W. Clarke gives an account of a simple 
mode of examining an alloy. A couple of years ago he made a few experi- 
ments upon indirectly determining the proportions of tin and antimony in 
alloys of the two metals. lie oxidised a weighed quantity of the alloy w r ith 
nitric acid in a porcelain crucible, heated the resulting oxides with amnionic 
nitrate, and tlun (regarding the tin as converted into Sn0 2 , and the anti- 
