66 Imperial Institute of France. 



of wine alone, very pure, is condensed in the last refri- 

 gerant. 



Jn this way, instead of heating at first in order to obtain 

 spirits of 19 degrees, from which we afterwards produced 

 by successive heats .spirits of different strengths, we have 

 all at once anv degree of strength we please. Besides, the 

 old-fashioned alembic only received two charges per diem, 

 wbereas that of Adam receives eight, and it extracts a sixth 

 part more spirit from the same quantity of wine : it saves 

 two fifths of the combustibles and three- fourths of the 

 manipulation, and finally the spirit which it furnishes has 

 never an empyieutnatic smell. 



With such advantages, it is not to be wondered that the 

 process in question has been so speedily and generally 

 adopted. M. Duportal, a chemist of Montpelier, has 

 presented to the Institute a very accurate description of it, 

 M'hich has been primed, and in which he also points out 

 certain improvements which have been suggested by 

 M. Isaac Berard. 



It is essential to notice, that the primitive idea of heating 

 by vapour belongs to Count Rumford, who published it in 

 London in 1798. It is thus that a simple general propo- 

 sition, which at first sight was regarded as an abstract truth 

 and without any useful application, may enrich whole pro- 

 vinces. 



Count Rumford, who has made so many useful disco- 

 veries, and who has made the a'conomizmg ol heat so 

 peculiarly his study, has this year presented to the Class 

 several useful memoirs upon lights. 



After describing various new forms of lamps, adapted for 

 decorating apartments and serving for chambers, lanterns, 

 8cc. without any of the inconveniences generally complained 

 of, he endeavours to resolve the great question which has 

 divided natural philosophers for upwards of a century, viz. 

 — Is li"ht a substance which emanates from lun)inous 

 bodies? or is it a movement impressed on thfse bodies by a 

 lluid in other respects imperceptible, and ditiused through- 

 out space ? 



As a given quantity of a given snt-cics of combustible 

 always gives out in burning one and the same quantity of 

 heat, it ought also, according to Count Rtunford, to give 

 out one aiici the same quantity of light, if the liijht werq 

 contained in it in the same way as heat is : for those even 

 who do not consider heat as a subsiance, admit thai it is a 

 force, a quantity of movement which may be co'Rcntred in 

 a body, and which issues from it in the same quantity in 

 wbiclj it was placed in it, as a spring unrolls itself. On 



th§. 



