III. OF THE PANS.

Fourteen pans may be made of iron, copper or earth. Sheet: iron is the best material. They should be round, one foot in diameter, with a rim pecked on four inches and a half high, and ought to have two small handles. They cost one dollar a-piece, in this city.

Having prepared this neceffary apparatus, the next thing is, to make use of it, in fuch a manner, as to refine the camphor.

Having taken the article out of the tubs, the glass vessels are, to be filled two-thirds full of it, and the apertures in the necks,, flightly stopped, with paper or cotton plugs. They are then,

to be placed on the bottom of the pans, and covered near to the base of their necks with fand.

The pans, holding the veffels containing the camphor, are to be carried to the fand-bath, and furrounded near to the top of the rim with fand.

A gentle fire is to be kindled in the furnace, at four o'clock in the morning, and gradually increased, until the camphor melts, which it does when it arrives at 304° of Fahrenheit's thermometer. It will first rise in flowers, which will diffolve, and run down the fides of the vessel. When it has melted, or is boiling, the glass is to be elevated in fuch a manner that the hot fand, may reach only to the middle of its belly, in order that the cool air may be admitted to the upper furface of the glafs, to congeal the camphor as it fublimes.

Having kept it in a liquid or boiling state, from eight to ten hours, the refined camphor will be found, adhering to the upper fide of the vessel, and is to be taken from it by breaking the glass while hot, or it may be kept until cool and then broken. The glass is easily separated from it, by means of a knife.

The foul parts which adhere to the bottom of the glass, and which cannot be easily parted from it, are to be broken into pieces, and fublimed a second time, with an additional fupply of camphor.

When the crude camphor is of a white colour, or contains little foreign matter, no addition is to be made to it; but when

it is brown or black, one ounce of flacked or quick lime, is to be mixed with every three or four pounds of it. The utility of lime in this operation, is noticed by Margraff.

One man can refine and pack up, from eighteen to twentyfive pounds every day.

If any of the glafs veffels holding the melted camphor should crack, which fometimes happens, and which is discovered, by the flowers rifing into the air from their fides and tops, the pans containing it are to be immediately removed to a cool place; and if the camphor is found mixed with the fand, the whole is to be put into other veffels, and the operation conducted as before.

The lofs in refining one hundred weight of this article cannot be accurately ascertained, as it depends upon the purity of the crude material, and the care in conducting the process. It cannot be very great.

Profeffor Robertson, in a note to Dr. Black's Chemistry informs us, that in a manufactory in Holland, he faw more than one hundred veffels in a furnace at one time, and that there was but a moderate fmell of camphor in the room.*

Hoping that this endeavour to make a very useful procefs, generally known in the United States may fucceed, and wishing you fuccefs in the establishment of your Medical Museum.

I remain, dear Sir,

Yours fincerely,

JAMES WOODHOUSE.

References to the Plate.

Fig. I. Is a fection of the furnace, fupporting a fand-bath. The afh-pit may be feparated, from the place where the fuel is lodged, according to the fancy of the manufacturer. The fuel. may be either wood, charcoal or pit-coal.

Fig. II. Is the glass vessel.

Fig. III. Is the iron pan, containing one of the veffels.

* Black's Chemistry, Vol. II. 351.

MEDICAL AND PHILOSOPHICAL

REGISTER.

FOREIGN AND DOMESTIC.

THE

HE following abstract of Meteorological Obfervations for fix fucceffive years, has been formed, with confiderable trouble, on the plan of the ingenious Profeffor Playfair, as detailed in the fecond part of the fifth volume of the Tranfactions of the Royal Society of Edinburgh. I have, however, made fix divifions in each month, of five days each, (except the last of thofe containing thirty-one days, and of February,) instead of three of ten days, as Profeffor Playfair has done. By making the divisions in these, twice the number, I have confidered it lefs necessary to extend the tables in other refpects, as is done in my model.

The column immediately following that of the month and its divisions, shews the highest degree of Fahrenheit's thermometer during each divifion. The next column points out the lowest degree for the fame period. The third column gives the mean temperature of the whole number of obfervations of each divifion; and the fourth is the mean temperature of all those means, or of the whole month.

The barometer follows, in like manner pointing out the higheft, lowest, and mean points of the mercury of each divifion, and the mean of those means, or of the whole month, in inches and hundredth parts.

For the most part, these instruments were noticed three times a day, from 6 to 8 in the morning, from 2 to 3 P. M. and at 10 at night.

The column of winds, points out the prevailing ones of the month, placed in the rank of their proportions, and none are noticed which did not exceed ten, in the monthly obfervations.

The proportion of clear and cloudy weather of each month, is attempted as nearly as poffible, by figures. In fome the proportions are accurate; in others, I might have extended the decimals to feveral figures; but fuch accuracy being unneceffary, I have purfued it no further than one point.-The number of times of rain, hail, fnow, &c. is only given as occurring at the hours of obfervation, without particularly fpecifying each: for as it often rained, &c. at other hours, when I did not notice it, this would at all events be imperfect. In fome inftances, the quantity of rain which fell in the month, was not attended to, and others, I have been unable to ftate, from having unfortunately loft, or mislaid them, in several times removing.

The thermometrical and barometrical obfervations having been rendered imperfect, from the fame caufe, I have been indebted for their completion to the kindness of Dr. Samuel Duffield, who has for feveral years kept a regular feries.

For these reafons I do not mention the fituation of the inftruments employed, which has been various; yet they have always been guarded from the fun, and its immediate reflection. It is however believed, that the obfervations are tolerably correct; and, as we have never had fo long a fucceffion of them published, it is prefumed they may prove interesting at a future day, to affift in determining what actual changes take place in our climate.

Editor.

February 8. River froze over, though several vessels went down the 5th and 7th.-The ice began to drive the 13th.-It was again fast the 19th, and drove the 21st.-By the 25th it was nearly gone, and several vessels went down.

March 13. Herrings in market-Shad the 20th.

April 20. First thunder storm, with hail and rain.

July 1. 2 3. Unusually hot.-On the 2d in some places the therm. was said to stand at 98°.-It fose to 1062 in the direct rays of the sun.-At 4 P, M. of the 3d, it stood at 94% -at 6 a violent storm which sunk it to 80o.

December 12.

Navigation obstructed.-Open the 14th.-Closed again 16th,