If then we could reckon upon a manufacture in which zinc would be constantly brought to the purest state, the manner, so completely proved, in which it is liable to be affected by all liquids, even cold, with which it forms compounds, which cannot be taken internally without some degree of danger, will not permit us to consider it as perfectly safe to be used for making vessels in which liquids are to be measured.

Conclusions relative to the Question contained in the Letter of the Minister of War.

Can zinc be employed with advantage in the place of copper for the vessels and utensils that are used in the military hospitals?

If the vessels and utensils, which are proposed to be made of zinc instead of copper, be destined only to contain water, although the Committee are convinced that pure water will attack this metal, in consequence of the experiments made on the vessels of M. Perrot, they might still be used to a certain point, when the oxyd of this metal may be given as a medicine, as far as the quantity of from 40 to 50 decigrammes, taken at different times in the course of a day, supposing that it did not remain more than the above time; for it must not be dissembled, that the daily conversion of a portion of metal into oxyd would not fail to occasion in the course of time an alteration, so much the more considerable as it would be favoured by the heat, and at length would render the vessels unfit for use.

But when it is proposed to employ these vessels in the preparation of food and drink, it is no longer the properties of the simple oxyd of zinc that are to be considered, but the properties of the saline compounds, which it forms with so much facility, both with the weakest acids and

with the salts which are always contained in the most common alimentary substances, and in the materials which are employed to season them; compounds which, like all metallic salts, are generally acerb, styptic, sour, emetic, some of them corrosive, and the use of which have never yet been directed in the pharmacopeia's, except as external remedies.

The assertion of M. Perrot, that, for two or three years, several persons have used his kettles and saucepans made of zinc without experiencing any inconvenience from them, cannot balance considerations equally weighty, founded on the principles established by the most 'celebrated authors, on the reports made to the Institute, to the Faculty, to the Committee of the Arts, supported by the experiments which the Commission was careful to repeat, with the most scrupulous exactness, on M. Perrot's vessels, and of which the results admit of no other conclusion, than that these vessels cannot without danger be employed in the preparation of food and drink.

The Class adopted these resolutions, and decreed, that they should be sent with the Report to the Ministers, who had written for information on this subject.

N. B. The following passage, extracted from the "Treatise of the Medical Police," published last year at Helmstadt, by Dr. Remer, will shew the opinion of the Committee of Health relative to the employment of zinc for vessels destined to prepare food,

"We have made experiments relative to the object of substituting zinc for tin, or for hardening tin by alloying it with this metal; but they have not succeeded; the composition is never uniform; it oxydates very speedily. It ought not, therefore, to be employed to cover copper, especially as the zinc dissolves in acids with more facility than tin. To cover copper with zinc is not better, be

cause

cause zinc oxydates as well as copper, its oxyd is very soluble in acids, and in that state it is very deleterious.”

We think it our Duty to place at the End of this Report the Letter of the Minister of the Interior to the Prefects of the Departments.

M. le Prefet. The Arts are indebted to Chemistry for the discovery of a new metal, which may be rendered of great utility, and merits encouragement. This metal is zinc, which has also been rendered malleable.

In recommending you to encourage the use of this metal, which may in many cases be substituted with advantage for tinned iron, lead, tin, and copper, I think it my duty, however, to acquaint you with the limits to which the use of it ought to be confined. They have been signified in a report which I have received from a Class of the Imperial Institute, relating to various questions, which I proposed to them in consequence of an application, requesting me to authorise the manufacture of this metal into the standard measures for liquids instead of tin. The conclusions from this Report are, that even if we could be certain that zinc would be always rendered perfectly pure, (that is, purified from the small quantity of arsenic that may remain combined with it,) the manner in which it is affected by all liquids, even cold, and the compounds which it forms with them, which cannot be taken internally without some degree of danger, does not admit of its being consideredas free from inconvenience for measuring liquids.

It is a necessary consequence of this conclusion, that vessels formed of this metal cannot be used without danger in the preparation of food and drink. It is, indeed, one that the First Class of the Institute mentions in the same Report, in answer to a question proposed by the Minister at War, and which was to enquire if zinc could

be

be substituted with advantage for copper in making vessels and utensils for the use of the Military Hospitals.

You will do well, therefore, Sir, to give an order to the examiners of the weights and measures not to admit to the examination any measures made of this metal intended for liquids; and, as for the vessels destined for domestic use, which may be manufactured of it, it is sufficient that I have acquainted you with the probable danger of employing it; and your zeal will guide you in the measures necessary to be taken, in order to preserve the health of the citizens of your department.

MICHAEL

List of Patents for Inventions, &c.

(Continued from Page 256.)

ICHAEL LARKIN, of Blackwall, in the parish of St. Dunstan, Stepney, in the county of Middlesex, Shipwright; for improvements in windlasses for ships and other vessels. Dated August 16, 1814.

HENRY WILLIAM VANDERKLEFT, of No. 253, High Holborn, in the county of Middlesex, Gentleman; for constructing a walking-staff, to contain a pistol, powder, ball, and telescope, pen, ink, paper, pencil, knife, and drawing utensils. Dated August 17, 1814.

ROBERT SALMON, of Woburn, in the county of Bedford, Purveyor; for improvements in the construction of machines for making hay. Dated August 22, 1814.

JOHN DICKENSON and GEORGE DICKENSON, of Nash Mills, in the county of Hertford, Paper-makers; for improvements in the said John Dickenson's patent machinery for manufacturing paper, and also a certain apparatus for separating the knots or lumps from paper or paper stuff. Dated August 24, 1814.

Specification of the Patent granted to JOHN LEWIS, late of Llanelly, in the County of Carmarthen, but now of Penclawild, in the County of Glamorgan, Assayer of Metals; for an Improvement in the Art of smelting Copper *. Dated July 23, 1813.

With a Plate.

To all to whom these presents shall come, &c. NOW KNOW YE, that in compliance with the said proviso, I the said John Lewis do hereby declare that the nature of my said invention, and the manner in which the same is to be performed, are particularly described and ascertained in and by the drawings hereunto annexed, and the following references or description thereof; that is to say: My invention of an improvement in the art of smelting copper ore consists in building my ore and metal furnaces between two calciners, and elevating the same above the said furnaces. Secondly; I cause the ore and metal, when calcined, to be conveyed,

* Patent granted "for certain improvements in the art of smelting copper."

VOL. XXV.-SECOND SERIES.

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