The best method of sampling such bars is to melt them all down and to take a dip sample of the molten metal in one or other of the methods already described. According to Mr. Claudet this should be done in all cases where the gold exceeds one or two ounces or where the silver exceeds 200 ozs. to the ton. If during the melting down some dross has formed this must be skimmed off, weighed and separately sampled and assayed. The clean lead also must be weighed, sampled and assayed. The mean result must be calculated. Thus 14 tons 5 cwts. of clean lead assaying 32 ozs. to the ton will contain 456 ozs. of silver; 15 cwt. dross assaying 20 ozs. to the ton will contain 15 ozs. of silver. The 15 tons of lead and dross will contain 471 ozs. of silver or 31.4 ozs. per ton. Of the methods of sampling which avoid melting the bars, that known as sawing is the only one which is thoroughly satisfactory. In it the bars are brought to a circular saw having fine teeth and are sawn across either completely or halfway through; in this way a quantity of lead sawdust is obtained (say 1 lb. or so from a bar) which represents exactly the average of the bar along the particular cross section taken and approximately that of the whole bar. A bar of lead, which by dip assay gave 334 ozs. to the ton, gave on three transverse sections 333 ozs., 335 ozs. and 331 ozs. The variation may be greater than this, but with a large number of bars, where each bar is cut across in as far as possible a different place, these variations tend to neutralise each other and a good sample is obtained. Two or three cwt. of sawdust may be obtained in this way; this is thoroughly mixed and reduced by quartering in the usual way or by a mechanical sampler. A sample of 2 or 3 lbs. is sent to the assayer. This being contaminated with the oil used in lubricating the saw is freed from it by washing with carbon bisulphide, ether or benzene and dried. Then, after mixing, 100 to 200 grams of it are carefully weighed and placed in a hot crucible, the heat of which should be sufficient to melt all the lead. The molten lead should not be overheated and should show no loss due to the melting. The removal of the oil may have decreased the weight by perhaps one half per cent. If the lead gives dross on heating it may be melted under 10 or 20 grams of potassium cyanide, which prevents the formation of dross. Samples are sometimes taken with a drill, gouge or chisel, though no method of this kind is quite satisfactory. One plan adopted is to use a punch which, when driven into the bar, gives a core or rod of metal about half as long as the bar is thick and about one-eighth of an inch across. With five bars side by side it is customary to drive in the punch at one end on the first bar, and at the opposite end on the last one, and on the others in intermediate positions in such a manner that all the holes will be along a diagonal of the rectangle enclosing the bars.