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E. J. ALLEN AXJ» E. W. NELSON. 



over into au inverted bell-jar, with a tubulure at tlie bottom, 

 into which the Berkefeld candle was fitted. Filtration under 

 these conditions was found to be rather slow, so in order to 

 increase its rate an apparatus was devised by which the 

 pressure on the filter was considerably augmented. 



This apparatus (see Fig. 1) consists of a glazed earthenware 

 '' tobacco jar," with two tubulures, one at the side, the other 

 at the bottom, and a lid which can be screwed down tightly 

 on to a rubber washer, by means of a triangular metal 

 arrangement fitting into grooves above the lid.^ The internal 



Fig. 1.— Dia;4ram of apparatus for pi'eparing sterile sea-water 

 l)y filtration, without contact with metal. 



dimensions of our jars are 1 1 in. by 6 in., and the diameter of 

 the opening at the top is 3| in. The tubulures are coned, 

 with the smaller diameter external, and make a good fit for a 

 No. 8 rubber bung. When setting up this apparatus a bung, 

 through which a short glass tube bent at right angles is 

 passed, is fitted into the side tubulure. This tube is con- 

 nected, by means of rubber pressure-tubing, to another glass 

 ' These jars were made to our specification by Messrs. Price, Powell, 

 and Company, Bristol. The clamps usually supplied with such jai-s are 

 not strong enough to obtain a tight joint. Ijnt these are easily replaced 

 by stronger ones. 



