72 



I)RS. J. A. HARKER AND P. CHAPPUIS ON A 



clamp fixed on the support of the l>ell-jar. The apparatus, filled with ice and protected 

 by a cover of thick flannel, can be left three or four hours without the least perceptible 

 change of temperature in the central part occupied by the reservoir 



XXVIII. STEAM-POINT APPARATUS. 



The 100-point apparatus, shown in fig. 16, is composed of a small boiler of 3 litres 

 capacity, communicating by a lead tube with a double walled vertical vessel, into 



Fig. 16. 



Fig. 17. 



" 



..t. 



Steam-point apparatus. 



V, reservoir of gas thermometer. 



0, copper boiler. 



E, double-walled cylinder. 



R, condenser. 



in. water manometer. 



Oil-lath far comparisons to 200. 

 E. The stirring arrangements are not shown. 

 U, copper oil vessel. 

 R, condenser. 

 V, air reservoir. 

 M, manometer. 

 C, wall of vapour bath cut away to show interior. 



which the thermometer reservoir can be introduced from above. The vapour 

 developed in the boiler first passes up the inner tube of the stearn bath, then 

 descends by the exterior annular space, finally arriving at the condenser, whence it 



