have a little pipe open at both ends as H H: this being soldered to a hole in the cover B B, is to be stopped at the top with a little valve P, exactly ground to it. This must be kept down with an iron rod I M, one end of which must be put into an iron staple M, fastened to the bar E E, and the other end kept down by a weight N to be hung upon it nearer or further from the valve according as you would keep it less or more strong, after the manner of an ordinary Roman balance, or steelyard.

"To know the degree of heat, I hang a weight to a thread about 3 feet long, and I let fall a drop of water into a little cavity made for that purpose at the top of it, and I tell how many times the hanging weight will move to and fro before the drop of water is quite evaporated.

"Experiment. Having filled my pot with a piece of a breast of mutton, and weighed five ounces of coals, I lighted my fire, and by blowing gave such a heat that a drop of water would evaporate in 4 seconds, the inward pressure being about 10 times stronger than the atmosphere: I let the fire go out of itself, and then the mutton was very well done, the bones soft and the juice a strong jelly. So that, having had occasion to boil mutton several times since, I have always observed the same rule, and never have missed to have it in the same condition, which I take to be best of all."

Beef required 7 ounces of coal and the same heat, and the beef was very well boiled, although there were more parts of the bones not quite softened. Lamb, rabbits, and pigeons, mackerel, pike, and eel, were subjected to the same process; whence the doctor infers that the bones of young beasts require almost as much fire as those of old ones to be boiled, that rabbit bones are

harder than those of mutton, that tough old rabbits may be made as good as tender young ones by this means, that pigeons may be best boiled with a heat that evaporates a drop of water in 5 seconds, that mackerel was cooked with gooseberries in a digester, the fish being good and firm, and the bones so soft as not to be felt in eating; and he particularly recommends, as an excellent dish cooked in this manner, cod fish and green peas.

The most important of Papin's experiments are those on the extraction of gelatine from bones, as now done on a large scale in France and in this country, as also the manufacture of essence of meat, soups, &c., especially suitable for long sea voyages.

"I took," says he, "beef bones that had never been boiled, but kept dry a long time, and of the hardest part of the leg; these being put into a little glass pot with water, I included in the engine, together with another little glass pot full with bones and water too, but in this the bones were ribs and had been boiled already. Having prest the fire till the drop of water would dry away in three seconds, and ten pressures, I took off the fire; and the vessels being cooled, I found very good jelly in both my pots; but that which had been made out of ribs had a kind of a reddish colour, which I believe might proceed from the medullary part, the other jelly was without colour like hartshorn jelly; and I may say, that having seasoned it with sugar and juice of lemon, I did eat it with as much pleasure, and found it as stomachical, as if it had been jelly of hartshorn." Mutton bones are better than beef bones; and he infers (1.) that one pound of beef bones afford about two lbs. of jelly; (2.) that it is the cement (gelatine) that unites the parts of the bones, which is dis

solved in the water to make it a jelly, since after that, the bones remain brittle; (3.) that few glutinous parts are sufficient to congeal much water, "for I found that when the jelly was dried, I had very little glue [-ten?] remaining; (4.) I used it to glue a broken glass, which did since that time hold very well, and can be washed as well as if it had never been broken; (5.) it is heavier than water, and sinks to the bottom; (6.) hartshorn produces five times its weight of jelly.

"From all these experiments, I think it very likely, that if people would be persuaded to lay bye bones, gristles, tendons, feet, and other parts of animals that are solid enough to be kept without salt, whereof people throw away more than would be necessary to supply all the ships that England hath at sea, the ships might always be furnished with better and cheaper victuals than they use to have. And I may say, that such victuals would take up less room too, because they have a great deal more nourishment in them in proportion to their weight. They would also be more wholesome than salt meat. Vegetables, such as dried peas, may also be cooked by the steam of salt water without becoming salt."

We have entered thus fully upon the work of Doctor Denys Papin, and the properties of his digester for cooking, and extracting jellies by high-pressure steam, because it contains nearly all that is at present practised in the preparation of food by steam.

If to what has been already stated, we add, that if the steam of salt water be collected in a vessel kept cold on the outside, the condensed water will not be impregnated with salt, and may be used as food, the importance of steam in the economical and menial capacity of cook, will

be sufficiently apparent. The supply of water to the crew of a steam vessel may be obtained in this manner, and an apparatus for thus procuring fresh water from the condensation of steam from salt water, has been used with advantage in ordinary ships.

Fig. 29 contains the steam-cooking apparatus used in modern kitchens; a a is a portion of the kitchen fireplace. In one of the divisions of it, b, is placed a steam boiler, furnished with the usual apparatus of feeding pipes, gauge cocks, &c. From this boiler a steam pipe, c c, is led along the back of the cooking table d d, and at certain intervals, branch pipes, furnished each with a stopcock, project across the table at right angles to the main pipe.

Fig. 29.

a

d

d

The extremities of these branch pipes are conical, and made accurately to fit into conical sockets inserted into the cooking pans, one of which, e, is seen in its place on the table. These pans have each a double bottom, the lower one close, the upper one perforated; between the bottoms the socket before mentioned, through which the steam enters, is inserted. The manner of using

this apparatus is simple. The article. The article to be cooked is laid in its place on the perforated bottom of the pan, the lid is applied, and the pan is joined to one or other of the branch pipes, by its socket receiving the conical end

of the pipe; the stopcock is now turned, and the matter in the pan is subjected to the action of the steam.

Each

being drawn off.