140 SEC. 5. MOLECULAR PHYSICS. 



brancs or porous plates, whose electric osmetic permeability is to be compared, 

 are placed between the cell and the glass vessels, the whole secured by two 

 brass vices. Both vessels and the cell are now filled with the same fluid. 

 Non-elastic partitions (clay plates, f. i.) must, in order to prevent breakage 

 and leakage, be provided, on each side, with an elastic ring (india-rubber or 

 bladder). 



Thin, very pliable, membranes f. i. skin of a frog, are secured between sieve- 

 like perforated plates of ebonite to prevent bending. 



The apparatus is used to demonstrate : 



1st, the fact of electric osmosis. 



2nd, the specific influence of the membrane ; the rise and fall of the fluid 

 in the cell shows which of the two membranes possesses a greater electric 

 osmotic permeability. On removing one of the partitions, the apparatus 

 becomes an ordinary osinometer. 



(Onderzoekingen gedaan in het physiologisch laboratorium der Utrechtsche 

 Hoogeschool. Derde Reeks, II., 1873, p. 365, etc.) 



632. Osmometer, illustrating the transpiration of gases 

 through capillary tubes. Prof. W. F. Barrett. 



This is an apparatus constructed under the direction of Professor Sullivan 

 for illustrating the law of the transpiration of gases. The diaphragm is 

 made of a number of short lengths of capillary tubes. 



IV. CONDENSATION AND SOLUTION OF GASES. 



633. Adams' Apparatus, for condensing and solidifying 

 carbonic acid. William Sykes Ward. 



634. Apparatus used in 1857 for Liquefying Ice by 

 Pressure at temperatures below 1 50 C. 



Prof. Mousson, Zurich. 



A small cylindrical recipient, hollowed out of a strong piece of steel, is 

 filled with water containing a movable metallic index. When the water is 

 frozen, the recipient is closed by means of a soft copper cone, subject to the 

 action of a strong screw. The apparatus is then reversed. The recipient 

 merges into a long, slightly widening cone of soft copper, on which a short 

 steel rod presses by means of a powerful screw-nut acting on the principal 

 piece, and a double lever a metre in length. If the recipient be opened, after 

 the pressure is removed, the index is found to have been carried over to the 

 other end, as a proof that the ice has been reduced to a liquid state. Soft 

 copper is the only means of closing under excessive pressures. 



The experiment can be successfully made at 18 C. 



635. Original Model of the Capillary Tube of Messrs. 



Poncelet and Lestros. Conservatoire dcs Arts et Metiers, Paris. 



636. Original Thilorier Apparatus for liquefying carbonic 

 acid, 1857. Conservatoire des Arts et Metiers, Paris. 



637. Apparatus for illustrating Boyle and Marriotte's law to 

 a class. Prof. W. F. Barrett. 



The mercury contained in the upper iron reservoir can be admitted to 

 the tube through an aperture closed by a valve that is moved by pulling the 

 string. 



