MOTIONS OF FLUIDS. gQj 



XIII. 



A Memoir on the Movements ivhich certain Fluids receive from 

 the Contadl of other Fluids *. jfifyJ.DRAPARNAUD, Curator 

 and Profejfor of Natural Hijtory, at the Medicinal School of 

 Montpelier. 



1 HAD obferved that alcohol attacks, and finifties by even, Experimenton 

 at length,, deftroying the calcareous covering of the mollufcas, alcohol which 

 which are put into it to be preferved. Suppofing that this led to the dif. 

 might arife from the alcohol, particularly that which is not i^^^{i°, 

 well redlified, containing a little acetous acid, I put a little 

 tindiire of turnfole into a glafs capfule, and poured into it a 

 a few drops of alcohol. The tinfture did not change colour, 

 but to my great furprife it moved towards the circumference 

 with great vivacity, leaving the bottom of the capfule un- 

 covered : when it had reached the maximum of difperCon, it 

 returned again, and covered the bottom of the velfel which it 

 had abandoned. It is evident, therefore, that mitfing what I 

 fought, I found that which I did not feek, which frequently 

 occurs in the courfe of experiments. 



This curious experiment induced me to make a multitude Prevoft'i me- 



r , , 1 r r 1 n a i iTioirs on the 



oi others, and to try a great number or lubltances. At the emanations of 

 moment of putting thefe experiments in order, and of com- odorant bodies* 

 pofing this memoir, I recolle61ed having read that M. BcneUidi 

 Prevoji had produced this repuifion of water by means of 

 volatile oils, and even of many folid odorant bodies. I there- 

 fore confulted the two memoirs which this ingenious phi- 

 lofopher has inferted in the Annals, and whofe fubjedt Is, The 

 methods of revdering the tmanatiom of odorant bodies fenfible to 

 the fig] it \. Although my experiments were made with another 

 view, 1 pafs over, in filence, all which are conformable to 

 thofe of M. Prevoji, and which I made by employing the fame 

 fubftances : I fhall only fpeak of thofe which differ from his, 

 either in the refults obtained, or in the means employed. 



1. If a thin ftratum of water is put on the bottom of a Aaion of alcohol 

 veflel, and a drop of alcohol is brought to the centre of this 



* From the Annales de Chimie. Fruftidor, An. XI, 

 t Amiales de Chimie. Tom. XXI. etXXIV, 



llratum. 



