Salting

The best safeguard against salting is to decide upon a plan for safeguarding samples and never to make any exception in carrying it out, whatever the circumstances; if an engineer trusts his judgment as to whether he is in safe company, his judgment is almost certain to be at fault at some time during his career, but if he always maintains the same vigilance he will never be salted. Salting is the result of carelessness, and is inexcusable.

The inclusion of waste samples is generally recommended as a safeguard, but like much good advice, is rarely carried out. The writer insists that no one except assistants whose integrity is known to him shall approach a sample until it is placed in a new, clean sack, and sealed, with the top turned over and tied down to prevent the working in of fine particles at the mouth of the sack. As a check upon a series of samples so taken, it is well to save a portion of the fines from rejected quarterings and to pan them; if a black greasy scum appears, it is evidence of tellurides; if a string of colors appears, its origin should be ascertained. After being sacked the samples should be locked in a mail sack, preferably made of leather, or in a trunk. If the sacks used are clean, a syringe cannot be used without detection through the stain left on the inside of the sack.

It is much better to offend the vendors by the precautions taken than to run any chances of being salted; those with honest intent seldom take offense at such precautions.

The Shipment of Samples.—Before shipping samples it is best if possible to grind them to a degree of fineness such that the assayer is sure to take a representative portion for assay; this is hard work, but it should not be left to the assistant of the assayer employed, who may not give proper care to this important work.

In shipping samples it is well to direct the assayer to reserve the pulp in case an umpire assay should be required, which will indicate to him that he is assaying against another man and will so induce accuracy. A duplicate set of samples should always be kept by the engineer. With low-grade ores it is best to instruct the assayer to make crucible assays on two assay-ton lots. Samples should be packed for shipment in boxes in preference to sacks.

It should be unnecessary to state that local assayers should be viewed with suspicion, and that the man who is to run the samples should be as thoroughly known to the engineer as any assistant whom he may entrust with the sampling. In large examinations an assayer is usually included in the staff.

Resampling.—It is usually advisable to resample personally a certain proportion of the cuts as a check upon assistants, as well as to check high assays.