We would follow with pleasure the reasoning and the discussions as if the subject were new but it is perhaps advisable to stop us a little on:
2° Dianémométre (and this despite an unlikely probable use as far as I am concerned) aiming to settle quickly and with precision main questions about the vapor supply. The drawer being led by a simple eccentric, an unspecified slide or the Deprez systems. ) See illustration). The general equation of the movement of a drawer led by an eccentric to infinite rod Is :
(this seems still quite topical since I have just met today a site web in Italian about the dianemometer)
We will not delay but pass to :
3° Nitroglycérine: it draws the attention of Jules Garnier from before 1869 for its activity in the problems of extraction of the ores but also for the manufacture of the torpedoes of which he will have to make use during the war of 1870 as major of engineering battalion. This substance gives, says him, so great advantages in the blows of mine that it was replaced the powder in several countries. He takes stock of the tests applied in Prussia, in Hamburg by Mr. Nobel and follows closely the result of the study trip of Mr. Levy charged by Mr.Combes of collecting information on its employment in the mines noting that one would have " seemingly found recently " the means of making nitroglycerin inexplosive by the only shock by mixing it with a particular alcoholic dyeing. The discovery is due to Mr. Sobrero who did it in 1860 in the laboratory of Mr. Pelouze in Paris by combining a nitrous acid concentrated with glycerin, product known for its decomposition of greases. He names this substance Pyroglycérine then Nitroglycérine. The proportion of the mixtures indicated by Sobrero was checked in the preparation on a large scale :
1 volume of nitrous acid 50° B.
2 volumes of acid sulfurous 66° B.
"One mixes in a vase, plunged in cold water, the nitrous acid of 40° with 50° B with the double of sulfurous acid. At the same time, one reduces glycerin until 30°B etc " Though it is approximately ten years later only that nitroglycerin had entered from the field of science to that of practice. We saw this same extension standing out in the metallurgy of the steel nickel.
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