A Note on a Still for the Preparation of Pure Water. — 

 By Harold S. King, A. B., Assistant Professor of Chem- 

 istry, University of Dalhousie, Halifax, N. S. 



(Presented 19 February, 1926) 



It is well known that glass is somewhat soluble in hot 

 water. Consequently the condensers used in the preparation 

 of extremely pure water by distillation must be of some other 

 material. Quartz and platinum are satisfactory in regard to 

 insolubility, but the former is fragile and the latter too ex- 

 pensive. Condensers of pure tin are perhaps the most practical 

 and are in general use both commercially and in the laboratory. 



This note is concerned with the connection between the 

 tin condenser tube and the distillation flask. T. W. Richards* 

 has pointed out that cork or rubber connections should not be 

 used, and has suggested that the tin pipe be bent so as to fit 

 into the constricted neck of the distillation flask, water effective- 

 ly sealing the union to prevent the loss of steam. 



The construction in the neck makes the filling and the clean- 

 ing out of the flask difficult. If the distillation is too rapid, 

 there is a chance that water that has been in contact with the 

 glass, and consequently contaminated with dissolved material, 

 may be swept by the current of steam up into and through the 

 condenser. Moreover, in case of breakage, a new flask with a 

 special neck has to be made. 



It has been found that if, instead of constricting the neck 

 of the flask, the end of the condenser tube be made large enough 

 to fit snugly into a flask of stock size, these difficulties are obvi- 

 ated. To accomplish this end, a block of tin, slightly larger 

 than the neck of the flask, was cast and machined down to fit. 

 A hole the size of the condenser was bored through one end of 

 the cylindrical casting and the other end was drilled out leaving 

 a mere shell. Finally the adapter, so made, was fused to the 

 curved end of the tin condenser tube with pure tin. A trap 

 to catch any spray that is formed in the boiling may be in- 



* Richards, Proc. Amer. Acad., 30, 380 (1894); Also see Richards and 

 Crail, J. Amer. Chem. Soc, 45, 1163 (1923) 



