2 Prof. R. Bunsen on a Method of determining the 



water, say from 170 to 200 cub. centims., poured in from an ac- 

 curate burette. The height of the water in the tubes is then 

 marked by a chalk line, and the tubes, having been emptied and 

 dried, are drawn out before the blowpipe to long ends about ] 00 

 millims. in length, and having a diameter in the thickened glass 

 of rather less than 1 millim. The end is then cut off square 

 with a diamond, and the edges rounded in the flame. Plate I. 

 fig. 1 represents such a vessel. 



Supposing that each of the vessels I., II., III.,, .has had its 

 weight in grammes R } , R 2 , R 3 determined, it is filled with water 

 by means of a hollow thread of glass connected to a funnel by a 

 caoutchouc tube. Let the weights of the tubes thus filled with 

 water be W v W 2 , W 3 , . . . ; then the capacity Y v V 2 , V 3 , . . . of 

 the vessels in cubic centimetres is 



I. . . W.-R^V,, 



II. . . W 2 -R 2 =V 2 , 



III. . . W 3 -R 3 =V 3 , 



IV. . . W 4 -R 4 =V 4 . 



If V 4 turns out to have the smallest volume, the capacity of the 

 other vessels, in order to be made equal to V 4 , must be dimi- 

 nished : 



I. by 



Vj-V* 



II. by 



v 2 -v 4 , 



II. by 



v 3 -v 4 , 



V. by 



v 5 -v 4 . 



This diminution of bulk is effected as follows: — A glass rod is 

 drawn out to fine solid threads of such diameter that they can 

 be passed through the capillary openings into the glass vessels. 

 If s represent the specitic gravity of the glass from which these 

 threads are made, we have only to allow the following weights 

 of given lengths of the threads to fall into the vessel to insure 

 that they shall possess the same capacity : — 



*(V,-V 4 ), 

 «(V,-V 4 ), 



S (V 3 -V 4 ). 



In the following Table the calibration of five such vessels is 

 given :— 



