Page:Popular Science Monthly Volume 16.djvu/746

 of the lot, they are by no means the only ones containing arsenical pigments. A recent number of the "Lancet" gives an account of an aggravated case of poisoning, due to a red paper on the walls of a sitting room; and arsenic has also been found in white, gray, blue, mauve, and brown wallpapers in abundance. As an instance of the utter disregard of consequences shown by manufacturers in the use of these pigments, we may cite the statement published by Miss Osborne, of the Sydney Hospital, New South Wales, that large quantities of poisonous pigments are consumed in that colony in coloring sweetmeats for children. We give in another place in this number a letter from a chemist in Pittsburg, showing an equally flagrant case of carelessness in the manufacture and use of arsenical papers for the operations of the kindergarten. People who thus disregard the welfare of their fellows, scattering poison broadcast in a way that neither age nor condition can escape, are, we submit, entitled to some small share of attention from the press, and from the courts.

Artificial Diamonds.—The "todo" about the artificial production of the diamond has been set at rest by Professor Maskelyne, who, in reply to numerous letters of inquiry on the subject, sends to "Nature" the results of his examination of the Macteor specimens which came into his hands for the purpose. He tested these so-called diamonds—1. With reference to their hardness; 2. Their refracting power; and, 3. Their combustibility. The samples sent to him were "too light to possess appreciable weight, too small even to see, unless by very good eyesight or with a lens," yet were sufficiently large to serve his purpose. "A few grains of the dust—for such the substance must be termed—were placed between a plate of topaz—a cleavage-face with its fine, natural polish—and a polished surface of sapphire, and the two surfaces were carefully 'worked' over each other with a view to the production of lines of abrasion from the particles between them. There was no abrasion. Ultimately the particles became bruised into a powder, but without scratching even the topaz. They were not diamond. Secondly, some particles more crystalline in appearance than the rest were mounted on a glass microscope slide and examined in the microscope with polarized light." They each and all presented powerfully the property of doubly refracting light. Finally, two of these microscopic particles were exposed to the intense heat of a table blowpipe on a bit of platinum-foil. They did not burn. They were afterward placed in contact with two little particles of diamond-dust, exceeding them in size, and the experiment, on being repeated, "showed that the diamond particles glowed and disappeared, while the little particles from Glasgow were as obstinate and as unacted on as before." When subjected to a stream of oxygen gas the result was the same. Hence, Professor Maskelyne concludes that the substance supposed to be artificially formed diamond is not diamond and is not carbon. Further experiments led him to the conclusion that it consisted of some crystallized silicate, or possibly of more than one such.

The fate of the Glasgow diamonds has induced Professor W. Mattieu Williams to send to "Nature" an account of his experience in diamond-making, for the benefit of those who may have an attack of the diamond mania. He states that for the popular class-room experiment of burning phosphorus in oxygen he used a cup of chalk, deeper and with a smaller rim than the brass cups usually made for this purpose—the object of this being to check too rapid outburst of combustion. He observed that a cup, several times used for this purpose, became coated on the inside with a hard, glassy enamel, which he supposed to be phosphate of lime. To test this, the cup was thrown into hydrochloric acid and dissolved, but at the bottom there remained a residue of insoluble crystalline particles. "Could it be possible that the carbonic acid, driven off by heating the chalk, had, in reaching the heated phosphorus, become dissociated, its oxygen combining with the phosphorus, and its carbon thrown down as veritable diamond?" These crystalline particles when tested were found to scratch a glass pestle and mortar in which they were rubbed, but were too small for further examination. To obtain a better supply, phosphorus was dissolved in bisulphide of