SCIENTIFIC SUMMARY. 
445 
author states that the great difference between sun and artificial light is due 
to the fact that, of the light emitted from the former, about half the quan- 
tity of rays are luminous and calorific at the same time ; but, as regards 
our artificial light, for ordinary oil (colza oil), the amount of non -luminous, 
yet calorific, rays is 90 per cent. ; for white-hot platinum, 98 per cent. ; 
alcohol flame, 99 per cent. ; electric light, 80, and gas-light, 90 per cent. ; 
while for petroleum and paraffin oils, the amount is 94 per cent. It is this 
large quantity of caloric rays in artificial light which causes the fatigue to 
the eyes; but this inconvenience may, according to the author, be almost 
entirely obviated by intercepting the thermic rays by glass, or, better yet, 
mica plates. The use of these renders the light soft and agreeable to the 
eyes. 
The Exact Comparison of Measures of Length . — It would seem from the 
second publication so long after the first one, that this paper is considered 
of importance. Illustrated with several engravings it was originally written 
and published by Herr. F. J. Stamliart, in Dutch, as far back as the year 
1839, but is here ( Chemical Neios ) reproduced in French at the suggestion of 
Professor F. Kaiser, partly in order to prove to M. Steinheil, of Munich, 
that the author (M. Stamkart) had, some thirty years ago, already in- 
vented what the German savant has lately described under the name of 
fuhlspiegel , and chiefly because M. Stamkart’s invention is of the highest 
importance just now for the purpose of aiding the exact reproduction of 
the standards of length (ei talon prototype) of the metre. 
Oxygen in Petroleum Wells . — It is stated by M. Widemann, who is con- 
nected with the works of the New York Oxygen Gas Company, that the 
use of oxygen in renewing and increasing the flow of oil in petroleum wells 
has been so successful that a regular trade has sprung up in oxygen gas for 
this purpose. The gas is injected into the wells through tubes, and, 
mingling with the hydrocarbon vapours, forms an explosive mixture, which, 
when ignited, completely opens seams which have become clogged, and thus 
renews the flow . — Scientific American. 
Temperature of Last Winter in Europe . — The recent experiments of Dr. 
Dove lead him to believe that abnormally low temperatures travel from 
East to West and abnormally high temperatures from West to East. He 
has proved this by various experiments during the past winter. 
Loss of a Distinguished Physicist . — The town of Mulhouse has just lost a 
very celebrated citizen, brother of the celebrated manufacturer, M. J. 
Dollfus. The deceased had left the pursuits of industry to devote his 
time entirely to science, and especially to geology and mineralogy. He 
was one of the most expert explorers of Alpine glaciers, and his extensive 
researches in science associate his name with those of Agassiz, Des Desor, 
and Des Martius. The deceased was a man of great wealth, and was 
highly respected by all who were acquainted with him. 
Further Researches on Cotton Respirators. — Dr. Jouglet has been experi- 
menting on the use of cotton respirators, and states that, by their application, 
the disease known as miner’s anaemia, and also the dangers of the effects of 
lead, copper, and mercury, to those who have to handle these metals, or 
work in vapours or dust thereof, may be .prevented. — Vide Comptes- 
renduSj August. 
