186 



Xew Hydraulic Machines, 



[March^ 



putting two colymos in equilibrio, the one of pure water, the 

 other of water mixed v/ith air. The last mixture, having a 

 smaller specific gravity than the first, can only counterbalance it 

 by means of a greater height. Hence it follows that the mixed 

 column ought to rise above the reservoir, and of course carry the 

 water which it contains above its natural level. 



This effect is not unknown to piiiiosopliers. It constitutes the 

 principle of the pump of Seville 5 and M. Cagnard-Latour has 

 already applied it to a machine in which he produces the mixture 

 of water and air by means of Archimedes's screw reversed; but 

 if the principle is not quite new, there is at least much novelty 

 in the manner in which M. Mannoury makes his mixture so as 

 to be very intimate. He is not satisfied with introducing a 

 volume of air into a volume of water. He wishes the air in the 

 first place to be divided into a number of minute bubbles, which 

 being lodged among the molecules of the water, should be kept 

 separate from each other, and retained by adhesion in such a 

 manner that they are only disengaged slowly, and do not unite 

 in order to escape till the object wanted by their presence has 

 been attained. 



M. Mannoiuy distinguishes two sorts of hydreoles; the hy- 

 dreoie by suction, and the hydreole by pressure. 



When a column of water moves in air, it drags a quantity of 

 the elastic, fluid with it, either in consequence of an adhesion 

 between the two, or because a species of vacuum is formed 

 round the column of water towards which the surrounding air 

 rushes. This last effect is demonstrated by the fine experiments 

 of Venturi. It follows from this that water, in passing through 

 a mass of air, absorbs a part of it, and becomes in some measure 

 gaseous ; and this is what M. Mannoury calls a hydreole by 

 suction. 



If on the contrary we suppose that a volume of air is driven 

 by force into a mass of water, by bellows, or any other means ; 

 and that this volume of air, in penetrating into the water, is 

 divided into a great number of small bubbles, by being made to 

 pass through very small lioles, the mixture that results is what 

 M. Mannoury calls a hydreole by pressure ; because in reality it 

 is by a strong compression of the air that it is forced to enter and 

 mix Vt'ith the water. 



In both of these hydreoles the water thus mixed with air 

 becofoes lighter than pure water, and of course capable of 

 mouTAting higher than the reservoir. Such is the basis of the 

 second method proposed by M. Mannoury. The author, as 

 usual, varies his applications. It will be sufficient here to point 

 O'at one or two. 



Let us conceive a reservoir to the bottom of which is adapted 

 a h'riiii tube^ orve branch of which rises higher than the reservoir* 



