At the back of the furnace there is a channel E, through which air is conveyed to the closet, which it enters at F. This channel being only separated from the fire in the furnace by a plate of iron G, the air, in passing through it, becomes heated before entering the closet. Between the bottom of the closet and the ash-pit of the furnace, there is a communication, H, which may be opened or shut at pleasure, by means of a sliding door or damper. Thus, on closing the external ash-pit door I, and opening the communication H, between the ash-pit and dryingcloset, a current of warm air is determined through the latter, for the whole of the air supporting the combustion in the furnace, passes through the channel E, in contact with the heated iron plate G, into the upper part of the closet at F, and ultimately through the opening H, into the ash-pit. This arrangement renders the drying-closet an exceedingly efficient one.

The Furnace Hood.-This is a contrivance for effectually getting rid of some noxious gases, such as those disengaged in the preparation of nitrate of copper, or sulphate of mercury. A is a cylinder fourteen inches in diameter, and eighteen inches high, made of galvanized iron, painted; it is open at the bottom, furnished with two handles attached to the sides, and one to the centre of the lid, and a door, as seen in fig. 7. The lid opens as represented in fig. 8, and immediately under the lid is a moveable plate C, which rests on a ledge, and has a circular hole, six inches in diameter, in the centre. About four inches from the bottom there is a ring six inches in diameter, attached by three supports to the sides of the cylinder, as seen in fig. 2 D. The furnace hood is intended to be placed over the open mouth of a ring-topped furnace, as shown in fig. 2. The lid being

opened, and the plate C removed, a Wedgewood dish, or other similar vessel, is introduced at the top, and placed on the ring D; the plate C is now returned to its place, and the ingredients to be operated upon put into the dish through the door, or through the opening at the top. The dish is of course exposed to the heat of the furnace, and any gas or vapour disengaged is carried into the furnace by the pressure of the superincumbent cold air, as shown in fig. 8.

Gas Furnaces, such as those represented in figs. 9, 10, and 11, are constantly used by the students. Those represented by figs. 9 and 10, are cylinders made of iron plate, japanned, with a small door for lighting or regulating the flame, a number of small holes round the top for the escape of the heated air, and openings at the bottom for the admission of cold air. These are placed over the gas burners attached to flexible tubes, as shown in the drawing, plate 2.

Fig. 11 represents a gas blow-pipe furnace.-A is a flexible pipe conveying gas into the tube B, which is open at its mouth. D is another flexible tube, conveying air from a double bellows fixed under the table, and worked by the foot, to the tube C, from the top of which it issues through a small opening in the middle of the tube conveying the gas. F and G are two stopcocks for regulating the supply of gas and air. The stop-cock F is first opened, and the gas lighted at the mouth of B. The stop-cock G is now opened, and a current of air forced into the middle of the gas flame by means of the bellows. A large blue flame is procured in this way, which affords an intense heat. The furnace H, which is similar to that shown in fig. 9, is placed as represented, and in the upper part of this, at E, there is a support for a crucible.

FIG. 12.

Fig. 12 represents a very convenient set of furnaces, applicable to a variety of purposes. They are fitted into an opening originally occupied by a common stove. Figs. 13 and 14 are horizontal and vertical sections.

We have now described that portion of the fittings and apparatus which we think most likely to interest or benefit our readers, either from their novelty or adaptation for the purposes designed. They have all been fitted up under Mr. Redwood's directions, and whatever originality may attach to any of them is due to him.

The following are the Regulations to be observed in the
Laboratory :-

1. The Laboratory shall be open from nine o'clock in the morning until six in the evening, daily, excepting Saturdays, on which day the studies of the pupils shall be conducted in the library and museum of the society. The pupils must quit the Laboratory by six o'clock to enable the assistant to proceed with the necessary cleaning and arrangements for the following day. 2. The professor shall assign to each pupil the operations to be performed, and shall provide the necessary apparatus and materials.

3. Such operations only shall be performed in the Laboratory as are sanctioned by the professor; and his directions must be followed by the pupils in the methods of conducting them.

4. The apparatus and materials required by the pupils will be supplied to them from the store-rooms by the assistant, who alone is authorised to take anything from the store-rooms, and he only by an order from the professor.

5. The pupils are required to use the apparatus and materials supplied to them, with care and economy; and in case of any wilful or culpable destruction or waste of the same, they will be called upon to pay for them.

6. The products of every operation are the property of the society; but the pupils will, on application to the professor, be allowed to retain specimens of those products which have been prepared by themselves.

7. Each pupil will have certain articles of apparatus given to him for his use, and he will be held responsible for the careful keeping and restoration of these. He is required always to clean the apparatus after using it; and to keep his work-table and utensils clean and in good order.

8. The pupils are required to conduct themselves in a quiet and orderly manner whilst in the Laboratory, or in the house of the society. The professor is authorised to suspend from further operations any pupil who shall be guilty of disorderly conduct, or who shall refuse to comply with these regulations; and the conduct of such pupil shall be reported to the next meeting of Council.

ORIGINAL AND EXTRACTED ARTICLES.

ANIMAL CHARCOAL AN ANTIDOTE TO POISONS. ON Monday, November 17th, 1845, Dr. A. B. Garrod read a paper before the Medical Society of London, on Animal Charcoal as an Antidote to various Poisons, especially those derived from animal and vegetable kingdoms. The following is an abstract of the paper, which will appear in the forthcoming volume of the Society's Transactions:

Dr. Garrod first noticed the experiments which had of late been made on the effects of animal charcoal in removing bitter principles from their solution, and then detailed his own experiments, which led him to use it as an antidote. The results he had arrived at were,

1st. That animal charcoal removed the active principles from vegetable and animal substances when added in proper quantities, even in a solution imitating the gastric juice, and at the temperature of the stomach (100° Fahr.)

2d. That animal charcoal will also form compounds with arsenious acid and other mineral substances, removing these from their solutions, and that it is quite equal, if not superior, to the hydrated sesquioxide of iron, as an antidote to arsenious acid.

3d. That the compounds of the animal charcoal with the poisonous principles have no injurious action on the animal body, and therefore, when the charcoal is given with the poison, or before it has become absorbed into the system, it will act as an antidote.

4th. A certain amount of the antidote is required, depending on the quantity of active principle contained in the poison, half an ounce is more than sufficient for twenty grains of nux vomica, or one grain of strychnia; if less is given, the poison may act by its excess above the antidote.

5th. The antidote is peculiarly adapted to poisonous substances whose activity depends on a small quantity of an active principle, as opium, nux vomica, the aconites, belladonna, stramonium, tobacco, hemlock, &c.

6th. The antidote itself may be given to almost any amount, as it exerts no injurious action on the body.

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7th. That it is of great importance that good animal charcoal should be used, not the bone or ivory black, which contain about 2 of earthy matter, but the carbo animalis purificatus of the London Pharmacopœia. Common bone black was found to be very far inferior, certainly not possessing a fifth of the antidotal power. The vegetable charcoal was comparatively inert.

Dr. Garrod proposes, that in cases of poisoning we should remove as much of the poison as possible by means of the stomach-pump or emetics, and then give a large quantity of the animal charcoal diffused in warm water, or the antidote may be given with the emetic, but ipecacuanha must not be used, as the charcoal would destroy its emetic property. Sulphate of zinc or some other mineral emetic should be chosen. Dr. Garrod also suggests that perhaps animal charcoal would prevent the action of the poison of rabies, syphilis, serpents, &c., if applied in the form of a poultice to the part which has come into contact with the poisons, and that it may prove serviceable as a remedy in some diseases, from its great power of absorbing all principles.