in THE PROSPECTOR'S HANDBOOK. 



up with the bulk of the ore, they are very apt to become 

 flattened out by hammering, and do not always present a 

 metallic appearance. In this condition they may refuse to 

 pass through the sieve, and an inexperienced person, not 

 understanding that they may be the most valuable frag- 

 ments of the sample, is inclined to throw them aside. In 

 reality, they should be collected together and most care- 

 fully examined. 



When fragments of the ore adhere to the mortar, a little 

 powdered coke or charcoal should be stirred about in the 

 mortar. 



When a dry assay or analysis is intended, the best sieve 

 to use is the one of sixty meshes to the inch ; when an or- 

 dinary wet assay, the eighty-mesh one ; but for the separa- 

 tion of heavy metals, such as gold, tin, &c., from the lighter 

 matter, by means of water and motion, the ore need not be 

 powdered very finely. A piece of fine muslin will, in the 

 absence of a sieve, answer ordinary purposes tolerably well, 

 if, when the powdered ore be placed in it, the muslin be 

 gathered together at the corners and shaken gently. After 

 the specimen has been thoroughly powdered it should be 

 put back into the mortar and stirred a few times by the 

 pestle in order to evenly distribute the light and heavy 

 particles, and then by a quick overturning of the mortar 

 deposited on a piece of dry paper (glazed if possible). The 

 powder may then be gently mixed by a knife or spatula, 

 and if there be too much in quantity divided into quarters, 

 and one or more divisions selected for the assay. The ore 

 can then be weighed very accurately on, the ore balance, 

 after which it is ready for assaying. If the assay is one for 

 gold and silver, the resulting button of precious metal is 

 naturally very small (and to weigh which the very delicate 

 button balance is used), so that great accuracy in the ori- 

 ginal weighing of ore is necessary, as the following calcula- 

 tion has to be made : If a weight of ore yields a certain 

 weight of metal, what weight of metal in ounces will a ton 

 of similar ore yield ? If the ore is assayed for ordinary 

 metals, such as lead, &c., then 



weight of resulting metal IQQ percentage of metal in 

 weight of sample of ore the ore. 



