CONTENTS. V 



VIII. On the Fetid Gas of Drains. - , - - p. 135 



IX. A Memoir, in which the Queftion is examined, whether Azote be a Am- 

 ple or compound Body? By Chriftopher Girtanner, Do£lor of Phyfic at 

 Gottingen. - - - - - - p. 137 



X. On the Power of the Oxygenated Muriatic Acid in Vegetation. By a 

 Correfpondent - - - - p. 140 



Scientific News, Accounts of Books, &c. - - p. 141—144 



An Account of the Irides, or Coronas, which appear around and contiguous to the Bodies of the 

 Sun, Moon, and other luminous Objefls. — A general View of the Nature and Objedsof Che- 

 mlftry, and of its Nature and Application to Arts and Manufactures. — Delcripdon of a 

 Telegraph. 



JULY 1800. 



Engravings of the following Obje£ts: 1. A new Statical Furnace for purifying 

 Copper. 2. Mr. Goodwyn's Engine for raifing Water; and, 3. Mr. 

 Howard's Apparatus for Exploding the new fulminating Mercury. 



I. Defcription of a new Method of extracting Silver from Copper-Mat by 

 Means of Lead, by which the Eliquation of Black-Copper is rendered unne-- 

 ceffary. By the late Dr. Gren, Prof, at Halle in Saxony. - p. 145 



The procefs confifls in roafiing fiilphureou.i copper ore to a Limited degree, and then fultng it with 

 lead in a blaft furnace, divided into two compartments, and communicating with each other by 

 a hole in the bottom of the wall or partition between them. In one compartment the pure lead 

 is fufed, and in the other the black copper or mat ; this lafl being kept charged fo high, that its 

 contents are gradually forced througli the partition into the lead, through which they rife, be- 

 caufc lighter ; and during this afcent, the filver contained in the copper is attrafled and ab- 

 lorbed by the lead by ftronger affinity. The copper is afterwards purified as ufual. 



II. Obfervations on the Proofs of the Huttonian Theory of the Earth, adduced 

 by Sir James Hall, Bart. By R. Kirwan, Efq. Communicated by the 

 Author. (Concluded from p. 102.) - - - p. 153 



III. On the Genuinenefs and Purity of Drugs and Medicines. By Mr. Fred. 

 Accum. (Concluded from page 36.) - - p. 159 



IV. Extracts of Letters from H. Goodwyn, Efq. on the Unities of Weight 

 and Meafure beft adapted to the Britifli Empire ; on the new Meafures of 

 France ; with a Defcription of an Engine for raifing Water. ~ p. 163 



The avoirdupois ounce is the thoufandth part of the cubic foot, and the Winchefter bufliel is very 

 nearly ten cubic feet. Proper Figure for a meafure.. Tables of Englifli arid French meafures. 

 Engine tor raifing v/atet on the principle- of the baroineter, 



V; A. 



