188 Kreider — A Convenient Apparatus for 



Art. XIII. — A Convenient Apparatus for Determining Vola- 

 tile Substances by Loss of Weight • by J. Lehn Kreider. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — cxxxiii.] 



Of the various forms of apparatus designed for the 

 determination of volatile products of reactions, some are 

 cumbersome and many require for their construction skill in 

 glass-blowing. The apparatus here described is light and 

 easily made from three test-tubes, modified and fitted as shown 

 in the figure. The test-tube, A, is changed in no 

 way from its original form ; B is perforated, in 

 the bottom, with a hole about l cm in diameter and 

 fits tightly within A ; and C, so selected that it fits 

 loosely within B, is drawn out to a small capillary 

 tube. 



When the apparatus is to be used, the capillary 

 of C is pushed through the hole of B, packed 

 loosely with cotton ; B is filled to the depth of 

 from 6 cm to 8 cm (about two-thirds of its contents), 

 with granular calcium chloride ; and B and C are 

 adjusted as shown. 



To the test-tube, C, is fitted a one-holed stopper, 

 through which passes a short glass tube which is 

 to be closed by a rubber cap and plug. Upon 

 removing the plug, and applying suction to the 

 short tube, the reagent employed to liberate the 

 volatile product to be determined is drawn up 

 through this capillary until C is sufficiently filled. 

 Upon replacing the plug the reagent remains within C, held 

 by atmospheric pressure. 



The tubes A and B may be so selected that very little of 

 the product evolved can escape between them, but in case they 

 fit very loosely, a ring of paraffine melted into the mouth of 

 A, about B, by means of a hot iron or wire, seals the joint 

 securely. A very convenient way to attach the paraffine is to 

 melt it between A and another tube, which fits A, as does B, 

 and may be removed by a turning motion, leaving the ring 

 into which B will fit, and which then requires very little heat- 

 ing to make a tight joint. If care be used in taking apart A 

 and B, at the close of an experiment, such a ring of paraffine 

 remains in place and may be used many times without replace- 

 ment, being remelted by a touch of the hot wire before every 

 new experiment. 



In making a determination, the substance under examination 

 is weighed and placed in the bottom of A. The reagent to be 

 employed, 10 cm3 to 15 cm3 , is drawn into C, and held there in the 

 manner described. The test-tube A is slipped over B, and 



