or Docimastic Hundred, in Metallurgy and Assaying, is a weight divisible, first into a hundred, and thence into a greater number of other smaller parts; but though the word is the same both with the assayers and metallurgists, yet it is to be understood as expressing a very different quantity in their different acceptation of it. The weights of the metallurgists are easily understood, as being of the common proportion; but those of the assayers are a thousand times smaller than these, as the portions of metals or ores examined by the assayers are usually very small.

The metallurgists, who extract metals out of their ores, use a weight divided into a hundred equal parts, each part a pound; the whole they call a centner or hundred weight; the pound is divided into thirty-two parts, or half ounces; and the half ounce into two quarters of ounces, and these each into two drachms.

These divisions and denominations of the metallurgists are easily understood; but the same words, though they are equally used by assayers, with them express very different quantities; for as the centner of the metallurgists contains a hundred pounds, the centner of the assayers is really no more than one dram, to which the other parts are proportioned.

As the assayers weights are divided into such an extreme degree of minuteness, and are so very different from all the common weights, the assayers usually make them themselves in the following manner, out of small silver, or fine folder plates, of such a size, that the mark of their weight, according to the division of the dram, which is the docimastic or assaying centner, may be put upon them. They first take for a basis one weight, being about two-thirds of a common dram: this they mark (64 lb.). Then having at hand some granulated lead, washed clean, well dried, and fitted very fine, they put as much of it into one of the small dishes of a fine balance as will equilibrate the (64 lb.) as it is called, just mentioned: then dividing the granulated lead into very nice halves, in the two scales, after taking out the first silver weight, they obtain a perfect equilibrium between the two scales; they then pour the granulated lead out of one dish of the scales, and instead of it put in another silver weight, which they make exactly equiponderant with the lead in the other scale, and mark it (32 lb.). If this second weight, when first put into the scale, exceed by much the weight of the lead, they take a little from it by a very fine file; but when it comes very near, they use only a whetstone to wear off an extremely small portion at a time. When it is brought to be perfectly even and equal to the lead, they change the scales to see that no error has been committed, and then go on in the same manner till they have made all the divisions, and all the small weights. Then to have an entire centner or hundred weight, they add to the (64 lb.) as they call it, a 32 lb. and a 4 lb. and weighing against them one small weight, they make it equal to them, and mark it (100). This is the docimastical or assaying centner, and is really one dram.