SCIENTIFIC SUMMARY. 
439 
tin-white, the streak greyish -black ; hardness, 4-5 ; sp. gr. 7-181. In contact 
with the air, the mineral tarnishes slowly, first assuming a blackish, after- 
wards a yellowish-brown, and finally a blue colour. An analysis made by 
R. Senfter, in the laboratory of Dr. Petersen, gave the following result: — 
Sulphur, 2-36 j arsenic, 66-90 ; antimony, 3 59; iron, 21-38; cobalt, 4-67 ; 
copper, 1*14 : total 100-04. The new ore belongs, consequently, to the 
group of arsenical pyrites, and comes nearest to the mineral from Wolfach, 
which Sandberger identified with Breithaupt’s geyerite. But, as neither 
form nor hardness, nor specific gravity and colour, are the same in both, and 
as, moreover, the copper observed in the new mineral is wanting in geyerite, 
Sandberger proposes, for this new ore from Guadalcanal, the name glauco- 
pyrite , and gives for its composition the formula — 
Fe\ » 
FeS, + 12(Co) 
(Co) j ^ 
The 11 Pochage ” of Cast Iron . — An interesting letter on this subject ap- 
pears from “T. B.” in the Chemical News of August 5. It says that this curious 
phenomenon is well-known to those engaged at blast-furnaces. The sparks 
are known by the workmen as “jumpers,” and their presence is usually held 
to indicate an approximation to white-iron. These sparks are absent during 
the running of grey-iron from the furnace, and only begin to make their 
appearance when the iron is about No. 4, the usual degree of greyness pre- 
ferred in South Staffordshire for puddling. The sparks are best observed 
during the running of white-iron from the furnace, especially if the molten 
metal is not very fluid, at which times he has frequently observed a vast 
number produced, particularly in the channel ; and sometimes, after the 
pigs have “set,” little jets of sparks are continuously discharged for many 
minutes, which discharge is accompanied by a hissing sound. M. Caron’s 
view may probably be correct, but he is inclined to attribute the production 
of these sparks to the combustion of carbon, and not of iron, as there is an 
entire absence of the peculiar scintillations displayed by burning iron. Yet 
one would almost be inclined to believe that grey-iron, which is supposed 
to contain uncombined carbon, would be more likely to exhibit this appear- 
ance than would white or mottled-iron. Yet, in grey-iron, and even in 
over- grey, or “ Kishy ” iron, there is an entire absence of these sparks. 
Important to Paraffin-Oil Producers . — The Association for Mineral Oils at 
Halle, in the Saale, desires to obtain information relative to : 1. The best in- 
formation concerning the chemical means of purifying crude paraffin cakes, 
so that the loss of paraffin does not thereby rise above 5 per cent. 2. A 
contrivance whereby materials containing paraffin may be cooled down at 
any season of the year to at least 5° C. In reference to No. 1, among other 
conditions are — that such substances as colourless tar oils, benzine, and, gene- 
rally speaking, any substances which either dissolve or alter paraffin, are ex- 
cluded from use ; the operation, moreover, ought to be readily executed and 
suitable for working on the large scale : the paraffin should be free from 
smell, and be of a bluish -white colour. In reference to No. 2, the con- 
trivance ought to be such as to enable to cool down daily at least 500 cwts. 
in quantities of 5 cwts. at a time. The Association is iuclined to give two 
premiums, each at 750/. value, for the best of the contrivances asked for, the 
