and the Fine Arts. 3C9 



rate the oxkIcs oiF iron, chrome^ and nickel ; but the oxide 

 of manganc.-;e, and the magnesia, if any be present, will rc- 

 niain dissolved. 



XII. To separate the oxide of manganese from magnc?ia, 

 pour into the fluid obtained in the last process hydrosul- 

 phuret of potash : the manganese will be precipitated, but 

 the magnesia will remain dissolved. The precipitated man- 

 ganese must be heated to redness, and weighed. 



XIII. To the fluid of the last process, from which the 

 manganese has been separated, add a solution of potash ; 

 the precipitate which now falls down is magnesia; let it 

 be waslicd, dried, and lieated to redness. 



XIV. In order to obtain the metallic oxides, boil the in- 

 fsoluble residue, left in Process XI, repeatedly in. nitric acid 

 to dryness. 



XV. Transfer the dry mass into a concentrated solution 

 of potash. The oxide of chrome, acidilicd in the last process, 

 will thus unite to the potash, but the other oxides will remain 

 untouched; decant the fluid from the insoluble residue. 



XVI. To separate the oxide of chrome, add to the solu- 

 tion muriatic acid in excess ; and evaporate the fluid till it 

 assumes a green colour : then, on addmg a solution of pot- 

 ash, the oxide of chrome falls down, because the quantity 

 of oxygen required for its acidification has been separated 

 by the muriatic acid : let the precipitate be dried and weighed* 



XVII. Let the insoluble residue of Process XIV be next 

 dissolved in muriatic acid, and to the solution add liquid 

 ammonia in considerable excess : the oxide of iron will be 

 precipitated ; let it be washed, dried, and weighed. 



XVIII. The oxide of nickel which remained in solution 

 on account of the excess of ammonia will now fall down : 

 on evaporating the fluid to dryness, its weight may be as- 

 certained in tbc same manner with the other ingredients, 

 and the analysis of the stone is now completed. 



JBlcmenls of Gdlvanism in Theory and Practice; with a 

 comprehensive Vieiu of its History, from the first Expe- 

 riments of Galvavi to the present Tivie : containing also 

 Practical Directions for constructing Galvanic Apparatus, 

 and plain Systematic Instructions for perfortning all the 

 various Experiments. Illustrated with Plates. By 

 C. II. Wilkinson'. 2 Vols. 8vo. 



The title of this work sufficiently explains its object. The 

 author, in his preface, mentions the sources whence he haS 

 chitflv derived his information, namely, the productions of 

 Sue, Keinhold, and Humboldt, and the Medical .lournal, 

 Mr. Nicholson's Journal, and the Philosophical Magazine ; 



\oi.. XVII. No. Cb. A a and 



