4 Harold N. Allen, 



of a short piece of wide brass tubing A, the lower end 

 being closed by a brass disc, while short brass tubulures are 

 soldered over three holes in the sides. B is a piece of brass 

 tubing ground into A, and having one-half of the lower part 

 cut away as shown. The top is closed by a brass disc, to 

 which the handle C is fixed. 



It will be seen that in the position indicated there is free 

 communication between the boiler and calorimeter in the 

 tap B, and between the calorimeter and still in C, which 

 is constructed on exactly the same plan. If both taps are 

 turned through i8o°, the vapor passes direct from B to C, and 

 so to the still, while by turning through a less angle part can 

 be made to pass through the calorimeter, the rest going 

 directly to the still. In this way the former amount can be 

 regulated. 



METHOD OF DETERMINING SPECIFIC HEAT. 



The order of an experiment was as follows : — 

 The upper cone was removed, the wire passed through the 

 small hole in the plaster of paris, the carrier and substance P 

 hooked on, the cone set in place on the instrument, and the 

 upper end of the wire hooked to the arm of the balance. 

 During this operation the wire was kept from rubbing against 

 the plaster by means of two small pieces of brass, which 

 filled the hole, leaving room for the wire in grooves on the 

 surfaces where they met. The balance, the pillar of which 

 was mounted on a tripod with levelling-screws, was then 

 shifted until the wire hung in the centre of the hole ; the 

 two halves of a wooden case surrounding the calorimeter were 

 pushed together, openings being left for the wire, the ther- 

 mometer, the steam pipe, and the escape pipe. The instru- 

 ment was then left for a long time (best over night) to take 

 a uniform temperature. 



The weight of substance and carrier in air having been 

 determined, and the thermometer in N read, removed, and 

 replaced by a cbrk, steam w^as admitted suddenly at L by 

 thrusting into the tubulure a tight-fitting brass tube, con- 



198 



