Page:Popular Science Monthly Volume 3.djvu/264

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252
THE POPULAR SCIENCE MONTHLY.

Builder calls enormous, and accordingly christens the new stone "Queen of Diamonds." But the Builder is plainly in error here, for there are many diamonds which weigh far more. Thus, the Grand Mogul is the owner of a rose-diamond which, in the rough state, weighed 780½ carats. It lost very largely in the cutting, weighing now only 136 carats. It is valued at over two and a quarter millions of dollars. A potentate in Borneo owns a diamond weighing 367? carats. The "Regent" weighed in the rough 410 carats. The "Orloff" weighs 19434, and may have weighed thrice as much in the rough state. An Austrian diamond weighs 139½, and, as the lapidary cannot cut these stones without depriving them of at least half their weight, it must have been, in the rough, larger than the Cape "Queen." But the name given to this newly-found stone will appear still more incongruous when we consider its quality. A diamond is said to be of the first water when it is perfectly limpid and colorless, and free from flaws, and of the second or third water in proportion as it departs from this standard. But this Cape diamond is of a yellow color, and marked with flaws—it is, therefore, not of the first water, and would in all probability be classed by the lapidary as of the third water.

 

Production of Sea-Salt in Portugal.—The salines of Portugal, at Setubal, Lisbon, Aveiro, and Algarve, yield annually 250,000 tons of sea-salt. According to Prof. Wauklyn, in the Mechanics' Magazine, the process of manufacture at the first-named place is as follows: There is a vast reservoir of about four acres in extent, eight inches deep, and partitioned into squares of about 130 yards in surface. Roads, three feet wide, separate the squares, and the latter all communicate with the main reservoir of seawater. In autumn the whole salt marsh is overflowed to the depth of 20 inches. This water evaporates in the spring, the roads appearing above the surface in June. Then the tanks are cleaned out, and afterward left to themselves, and recharged from time to time with new supplies of water. In 20 days a layer of salt over one inch thick is found. This, the first crop, is collected, and the tanks filled again. In 20 days another crop is gathered. If the season is favorable, three crops may thus be collected before September, when the marsh is flooded for the winter.

 

Controlling Sex in Butterflies.The American Naturalist for March contains an admirable essay by Mrs. Mary Treat, in which she brings a long array of facts to prove that the sex of butterflies depends, in some cases at least, rather upon the external conditions surrounding the larva, or caterpillar, than on its anatomical structure. The results of the author's experiments contradict the doctrine of most entomologists, which asserts that even in the eggs of the Lepidoptera the germs of sexual difference may be discerned. The editor of the Naturalist quotes from several authorities, to show that, in the case of all animals which reproduce by eggs, the sex is probably determined at or about the time of conception, or at least early in the embryonic stage. Mr. T. W. Wonfor also, writing on "Certain Wingless Insects," in Hardwicke for March, asserts that the very same conditions, viz., lack of abundant food, or alternations of scanty and bountiful food, which, according to Mrs. Treat's experiments, determine the sex of the future imago, or butterfly, tend only to "produce dwarfs or monstrosities." The writer in Hardwicke, we may add, holds that no sex-difference is discernible either in the eggs or in the larvæ. Mrs. Treat's observations and experiments, it will be seen, were very thoroughgoing and very carefully conducted, and will, doubtless, attract the earnest attention of naturalists. Some two years ago Mrs. Treat placed a larva, which had already taken some steps toward the chrysalis state, upon a fresh stem of caraway, and was surprised to see it commence eating. It then continued to eat for some days before changing to a chrysalis. She next placed a number of other larvae on similar stems of caraway, while still others she deprived of food altogether. Those of the last lot which completed their transformations were all males, and all the butterflies from the first lot were females.

The next experiment was commenced in June last. In July the author had about two hundred larvæ feeding at once. Im-