Technology. 
431 
1876.] 
The optical and crystallographical properties and chemical composition of 
microcline, a new species of triclinic felspar with a potassic base, have been 
described by M. des Cloizeaux. The™composition of this mineral is — Silica, 
64*30; alumina, 19*70; ferric oxide, 0*74; potash, 15*60; soda, 0*48 ; loss on 
ignition, 0*35. The specific gravity is 2*54. 
TECHNOLOGY. 
Dr. H. D. Meidinger contributes a valuable paper, on “ Progress in the 
Artificial Production of Cold and Ice,” to Dr. A. W. Hofmann’s “ Report on 
the Development of the Chemical Arts during the last Ten Years.” Speaking 
of the preservation of ice, he says that ice machines, however they may be 
eventually improved and their effed increased, will never, in the more northern 
parts of the temperate zone, where a moderately cold winter with frost is 
generally experienced, acquire importance enough to meet the demand even 
approximately. They will serve merely as valuable substitutes to render us 
independent of the fickleness of the seasons. Even in more southern regions, 
where ice machines are the only source for obtaining ice, they must work to 
stock and fill magazines, since the demand does not go hand in hand with the 
production, but varies with the weather. There is in general no conception 
of the quantities of ice which certain trades require, and which are consumed 
in domestic life where its use has grown into a necessity. In 1866 the quan- 
tit)' of ice consumed in New York and its vicinity amounted to 250,000 tons 
(254,015 metric tons), or 5 cwts per head. The weight stored up was 
543.000 tons (551,721- metric tons, whilst the capital employed in the trade 
amounted to 2,160,000 dollars. The retail price was for quantities of 5 to 12 
kilos. 4 pfennige (the German u pfennig ” is about the tenth part of an English 
penny) per kilo., but for quantities of 1 to 10 cwts. only one shilling per cwt. 
In 1871 a company in Berlin, the “ North German Ice Works,” stored up 
600.000 cwts. of ice, and delivered it to subscribers at 77 pfennige per cwt. 
The quantities of ice consumed in brewing may be learned from the following 
data, which the author obtained in 1869 from Dreher’s brewery at Klein 
Schwechat, near Vienna : — This establishment brewed, in 1867, 483,150 
Viennese eimers, = 273,463 hedolitres, and stored up 515,600 cwts. 
(28,874,219 kilos) of ice. In the following year these numbers rose to 
492,499 eimers (278,754 hedolitres) of beer and 563,058 cwts. (31,531,924 kilos, 
of ice. On an average 1 cwt. of ice is used per eimer (56.6 litre). In a pro- 
longed frost of 2 months this quantity can be procured at the cost of 7 
Austrian kreutzers (14 pfennige) per cwt. In shorter periods of cold the 
I price rises to from 10 to 12 kreutzers, to which must be added 1 kreutzer for 
shovelling into the ice cellars. In mild winters the ice is brought in part from 
Styria ; as the cold weather in 1869 set in late, 26,000 cwts. (1,456,031 kilos.) 
i were procured from there, costing, by the time it reached the brewery, 115 
florins per 200 cwts. 
Schweinfurt-green, known also as mitis-green and mountain-green, is 
a compound of the arsenite and acetate of copper too frequently 
used, in spite both of advice and of legal prohibition, for colouring paper- 
hangings, ball-dresses, artificial flowers, wafers, bon-bons, and toys. 
Every winter we hear of needlewomen experiencing serious affedions after 
having made up costumes of tarletan coloured 01 printed with Schweinfurt- 
green ; that dancers wearing similar materials, and with wreaths of artificial 
flowers in their hair, experience violent headache on the morning after the 
ball ; that similar symptoms have been experienced by persons who have 
slept for some nights in rooms papered or painted with green ; and, lastly, 
that children have been seized with vomiting after having eaten bon-bons or 
sucked toys coloured green. M. Kupfferschlseger recommends the following 
method of detedion : — The stained paper, divided into strips, is placed in a 
porcelain soup-plate, and covered with a solution of chlorate of potash 
saturated when hot, and the whole is heated in the water-bath till the paper 
is completely dry. Then it is set on fire, and instantly covered with a large 
glass bell so that nothing may be lost. The ash is pulverised, and imme- 
diately exhausted in the cold with the water which has served to rinse out the 
