A XX US' S CALORIMETER. 



39 



As described by Mr. Barrus, "it consists of a glass beaker 

 (Fig. 12) 5 inches in diameter and II inches high, which 

 can be obtained of most dealers in 

 chemical apparatus. The combus- 

 tion-chamber is of special form, and 

 consists of a glass bell having a 

 notched rib around the lower edge 

 and a head just above the top, with 

 a tube projecting a considerable dis- 

 tance above the upper end. The 

 bell is 2\ inches inside diameter, 5^ 

 inches high, and the tube above is f 

 inch inside diameter and extends 

 beyond the bell a distance of 9 

 inches. The base consists of a cir- 

 cular plate of brass 4 inches in diam- 

 eter, with three clips fastened on 

 the upper side for holding down 

 the combustion-chamber. The base 

 is perforated, and the under side 

 has three pieces of cork attached, 

 which serve as feet. To the centre 

 of the upper side of the plate is attached a cup for holding 

 the platinum crucible in which the coal is burned. To the 

 upper end of the bell, beneath the head, a hood is attached 

 made of wire gauze, which serves to intercept the rising 

 bubbles of gas and retard their escape from the water. The 

 top of the tube is fitted with a cork, and through this is 

 inserted a small glass tube which carries the oxygen to the 

 lower part of the combustion-chamber. This tube is movable 

 up and down, and to some extent sideways, so as to direct 

 the current of oxygen to any part of the crucible and to 

 adjust it to a proper distance from the burning coal." 



The method of working it can be easily seen from the 

 description and cut. In burning very smoky coals he mixes 



FIG. 12. BARRUS CALORIM- 

 ETER. 



