The grease containing the diamonds, together with a small percentage of very heavy minerals, such as iron pyrites and barytes, is scraped from the tables, placed in buckets made of steel plates with fine perforations, and boiled or steamed. The grease passes away to tanks of water, where it is cooled and is again fit for use. The diamonds, together with small bits of iron pyrites, brass nails from the miners’ boots, pieces of copper from the detonator used in blasting, which remain on the tables owing to their high specific gravity, and a very small admixture of worthless deposit which has become mechanically mixed with the grease, are then boiled in a solution containing caustic soda, where they are freed from all grease. The quantity of deposit from the size of ⅝ of an inch downwards, which now reaches the sorting table, does not exceed 1 cubic foot for every 12,000 loads (192,000 cubic feet) of blue ground washed. As already stated, 5/12 of 1 per cent of the whole mass of blue formerly passed to the sorting tables; or, from 12,000 loads, which is about the daily average of the quantity washed at De Beers and Kimberley Mines, 800 cubic feet had to be assorted by hand. THE YIELD OF DIAMONDS Sometimes as many as 8000 carats of diamonds come from the pulsator in one day, representing about £20,000 in value. When the bare statement is made that nearly 5,000,000 truck-loads, or more than 4,000,000 tons of blue ground, have been washed in a year, the mind only faintly conceives the prodigious size of the mass that is annually drawn from the old craters and laboriously washed and sorted for the sake of a few bucketfuls of diamonds. It would form a cube of more than 430 feet, or a block larger than any cathedral in the world, and overtopping the spire of St. Paul’s, while a box with sides measuring 2 feet 9 inches would hold the gems. From two to three million carats of diamonds are turned out of the De Beers mines in a year, and as 5,000,000 carats go to the ton, this represents half a ton of diamonds. To the end of 1892 10 tons of diamonds had come from this mine, valued at £60,000,000 sterling. This mass of blazing diamonds could be accommodated in a box 5 feet square and 6 feet high. The diamond is a luxury, and there is only a limited demand for it throughout the world. From four to four and a half millions sterling is as much as is spent annually in diamonds; if the production is not regulated by the demand, there will be over-production, and the trade will suffer. By regulating the output the directors have succeeded in maintaining prices since the consolidation in 1888. The blue ground varies in its yield of diamonds in different mines, but is pretty constant in the same mine. In 1890 the yield per load of blue ground was: