Page:Proceedings of the Royal Society of London Vol 1.djvu/460

Rh and his descriptions are accompanied with drawings of various peculiariti of structure.

0f the birds that live on animal food, the author has examined several kinds of falcon, the Soland goose, the crane, the cormorant, the common gull, and the snow-bird, the last of which differs considerably from the rest.

Among graminivorous birds, the swan and goose are noticed as diﬁeﬁng from most others in the situation and structure of these glands. Others of this tribe here examined are the turkey, the cassowary, the American ostrich, and the African ostrich. In the three last the solvent glands are in a cavity of unusual size; and the mus- cular structure of the gizzard is uncommonly weak, which the author conceives to be connected with the mode of progressive motion, which is the same in these birds, and may serve to grind the food without the assistance of strong muscular action.

The author has formerly described to the Society two compounds, consisting of phosphorus and oxymuriatic acid, or chlorine; one of them is a solid compound; and by his present experiments, consists of three parts of phosphorus combined with twenty of chlorine. The second compound contains only half this quantity of chlorine, and is a ﬂuid, having the speciﬁc gravity of 1'46. The ﬂuid will also dis~ solve a still further quantity of phosphorus; but the author has not ascertained whether there is any deﬁnite limit to the proportion so dissolved.

When this ﬂuid compound is treated with water, it forms a thick ﬂuid, of the consistence of syrup, that crystallizes slowly by cooling. These crystals maybe called hydrophosphorous acid; for hy heat they are decompounded into phosphoric acid, and a peculiar gas, consist- ing of phosphorus and hydrogen. This gas diﬂ'ers from common phosphuretted hydrogen, in not being spontaneously inﬂammahle when mixed with common air, and in being considerably less fetid than that gas. The proportions of its constituent parts are estimated to be four hydrogen, with twenty phosphorus. The phosphoric acid contained in the crystals, derived its origin from the water added to the original ﬂuid; while the hydrogen of the water escaped with the chlorine in the form of muriatic gas.

In the interchange of elements which takes place in these combinations, there are many circumstances favourable to ascertaining the proportions in which the several elements unite with each other; and the author observes, the results accord remarkably well with other determinations.

In the same manner respecting sulphur, a similar accordance between the proportions, by weight, in which it unites with different elements, conﬁrms other estimates of the elementary number ﬁt to