1824.] New Scientific Books. 97 



which dissolves the metallic copper of the alloy to a certain 

 depth on the surface, so that after the operation the metal is in 

 fact gilded, nothing but pure gold being visible. In this pro- 

 cess the waste of gold, which is dissolved by the acid, in the 

 process usually employed, is avoided. 



Dr. Mac Culloch observes, " that it is an unaccountable 

 omission of chemists not to have observed that metallic copper 

 is soluble in ammonia. The solution takes place rapidly in the 

 heat at which the water of ammonia boils." 



Copper-plates are apt to be injured by laying by ; a thin coat 

 of oxide forms on the surface, which is rubbed off by the hand 

 of the workman in the first inking, when the plate is again 

 called into use ; and by repetition of the formation of oxide, and 

 its removal, the fine lines on the plate are soon injured, and 

 ultimately obliterated. Dr. Mac Culloch recommends the ap- 

 plication of common spirit varnish to the surface when the plate 

 is laid by ; it is easily applied, and can be removed when requi- 

 site by spirit of wine. — (Edinburgh Journal of Science.) 



Article XV. 

 NEW SCIENTIFIC BOOKS. 



PREPARING FOR PUBLICATION. 



The Fourth Volume of the New Series of the Memoirs of the Man- 

 chester Literary and Philosophical Society. 



A Compendium of Medical Theory and Practice, founded on Dr. 

 Cullen's Nosology, which will be given as a Text Book. By D. 

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Muscologia Britannica: containing the Mosses of Great Britain and 

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 MRIA. FLS. &c. 8vo. With Plates. 



Mr. Swainson will speedily publish in an octavo volume, with six 

 Plates of the most beautiful humming Birds of Mexico, the ;< Zoology 

 of Mexico," illustrated by general Remarks and scientific. Descrip- 

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 work is intended as an Appendix. 



JUST PUBLISHED. 



Wade's Observations on Fever. 8vo. +s. 



Woodford's Catalogue of Phaenogamic Plants in Edinburgh. 12mci, 

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Harrison's Surgical Anatomy of the Arteries. Vol. I. ]2mo. SS* 



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