Prof. Chapman on the Assaying of Coals by the Blowpipe. 437 



ing the nature and amount of ash, pyrites, &c., see under § 3 

 below. 



§ 2. Instruments and Appliances. 



The instruments, &c. employed in these examinations are 

 the following: — a blowpipe, blowpipe-lamp, and small spirit-lamp 

 of the ordinary construction ; together with the usual accessory 

 instruments and reagents which always accompany the blowpipe. 

 These require no special description. The blowpipe may be of 

 any form ; but for the purpose of heating small platinum vessels 

 in these experiments, it is convenient (although not absolutely 

 necessary) to add to it an extra jet with an orifice rather larger 

 than usual. The blowpipe-lamp should also be furnished with a 

 broad wick-holder of the pattern recommended by 

 Plattner (fig. 1), in place of the flat wick -holders 

 formerly in use. In heating crucibles it is advi- 

 sable to turn the wick-holder so as to make the 

 upper surface slope towards the right-hand instead 

 of towards the left, the flame being then directed 

 upwards, against and around the bottom of the 

 crucible. Or, to avoid the trouble of changing 

 the position of the wick-holder, the operator may 

 turn the lamp itself, placing it with its fore part away from him. 



In addition to the above, the following appliances, of more 

 special use, are also needed : — (1) Two platinum capsules as 

 thin as they can be obtained. One about half an inch in dia- 

 meter, provided with a small ear or handle; and the other of 

 somewhat smaller dimensions, and without any projecting ear. 

 The smaller capsule, reversed, fits into the larger one, the two 

 then constituting a closed vessel. Those which t employ, weigh 

 together less than 42 grains. (2) A small platinum crucible 

 with a lid. I make use of two small but deep platinum spoons; 

 one with, and the other without a handle. The latter must be 

 the larger of the two. Its edges must be bent slightly inwards 

 so as to allow it when reversed to be fitted closely over the 

 smaller spoon, and thus to constitute a lid. The long handle of 

 the spoon crucible should be bent as shown in fig. 2. The 

 object of this is to enable the crucible to retain 

 an upright ])osition when placed on the pan of 

 the balance. The figure shows the exact size and 

 form of the crucible employed by me. Its weight! 

 is a little under 3G grains. In some spoons a! 

 slight notch must be cut in the lid to admit the 

 passing of the handle. (3) A pair of steel tongs 

 or forceps to hold the platinum vessel during ignition. These 

 tongs should be so constructed as to remain closed except 



