SCIENTIFIC SUMMARY. 
219 
Sul 2 :)hur in the Smelting Districts . — The sulphurous smoke in the copper- 
smeUing districts, such as Swansea, which formerly destroyed the sur- 
rounding vegetation and impaired the health of the people, is now turned to 
profitable account in the production of sulphur. Copper and iron pyrites 
contain from 40 to 60 per cent, of sulphur, and it is reckoned that sulphur 
of the value of half a million sterling may be annually obtained from sources 
heretofore not merely useless, but pernicious. 
Bronzing hy Aniline. — The aniline dyes have been used as a means of pro- 
ducing an artificial bronze. When employed in a concentrated solution, and 
painted in objects, they give a somewhat bronzed appearance. 
The Strpyosed Dangers of Nitroglycerine. — Give a dog a bad name and 
hang him,” says the proverb. This is true enough in the case of the nitro- 
glycerine subject. Because a few serious accidents have occurred, all sorts 
of absurd and imaginary evils and dangers are associated with this substance, 
and really most of the accidents have been caused by that extreme ignorance 
which is characteristic of some people, and which would lead to serious 
accidents with almost any new substance. Hear what Mr. Nobel, the in- 
ventor, has to say. He gives the following illustration : — In five cases 
congealed nitroglycerine has been melted purposely over fire. In three 
cases a red-hot poker has been inserted into the oil in order to melt it. 
In one case a man took to greasing the wheels of his waggon with nitro- 
glycerine, knowing what it was, and it went all right until it struck hard 
against something, and then the wheels went to pieces. In one case it was 
burnt in a lamp as an improvement on petroleum. In these days every mis- 
chief is charged to nitroglycerine. Thus we read in the Northern Evening 
Express, that recently a box with nitroglycerine exploded at a railway station 
in the city of Berlin, ‘ and that the simple act of placing it in the van caused 
it to explode.’ It is a proved and confirmed fact that it was fulminate of 
mercury that exploded.” Nitroglycerine, Mr. Nobel says, has been accused 
of spontaneous combustion, but the truth is that, unless properly purified, it., 
emits a nitrous odour, and will gradually decompose during some years. The 
nitroglycerine, however, now made by him is always pure, he writes- 
chemically pure ” ; it is obtained by crystallisation from wood naphtha. — 
Chemical News, January 3. 
Lead Floating on Molten Iron. — Experiments lately made in Germany 
seemed to show that molten lead, though really denser than iron, would 
nevertheless float on molten iron. Professor Kamarsch, however, put the 
matter to the test by examining a block of cast-iron, supposed to contain 
drops of lead lying upon the surface. Professor Kamarsch found, upon close •• 
examination, that these drops of lead, instead of being solid globules, as was 
supposed at first sight, were all found to be hollow, forming bubbles com- 
posed of metallic skin, and apparently empty in the centre, so far as his 
observation was carried. He explains the whole by supposing that the 
molten lead, at the temperature to which it is raised by the contact with 
the liquid iron, forms an incipient vapour of lead, which is prevented from- 
escaping by the skin of solidifying metal which forms on the top. The 
lead vapour, according to this explanation, keeps the lead resting upon the 
surface of the iron. It seems that in large quantities the result is different, 
since it is known that lead is occasionally tapped from the bottom of tho 
blast furnaces which smelt certain classes of ores containing lead, and in 
YOL. YII. — NO. XXYII. Q 
