542 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



the establishment of the inventor. The process of manipula- 

 tion, without entering into too minute detail, is as follows, 

 premising that the time required for the completion of the 

 operation is less than one tenth of that by the old method. 



The platinum solution is prepared by taking 100 grammes 

 of this metal in thin sheets (a gramme being equal to about 

 15^ grains), which are first wiped off and washed to remove 

 the grease which may have become attached during the proc- 

 ess of lamination, and then dissolved in aqua regia, formed 

 by a mixture of 400 grammes of nitric acid and 1000 grammes 

 of pure hydrochloric acid. The solution is heated in a sand 

 bath and evaporated to dryness, and then reduced to powder, 

 upon which rectified essence of lavender is then to be poured, 

 little by little. When about 1400 parts of essence of laven- 

 der have been added, the mixture is to be removed and placed 

 in a porcelain capsule, and allowed to remain eight days in 

 absolute rest. It is then to be poured off, and the filtered 

 liquid decanted anew six days afterward, and then again after 

 another period of six days. As a flux for the quantity of 

 platinum above given, 25 grammes of litharge and 25 

 grammes of borate of lead are to be pounded up in eight or 

 ten grammes of essence of lavender. This combination to be 

 added to the platinum liquid, which is now to be applied to 

 the surface of the glass, held vertically, by means of a brush. 

 The brush is to be applied thoroughly in all directions, from 

 the top to the bottom, from the bottom to the top, and then 

 from right to left and left to right, so as to equalize, as much 

 as possible, the oily coating, which contains a large percent- 

 age of lavender, so that it may dry without wrinkling. 



In this operation dust and moisture must be carefully 

 avoided, as the former will render the surface uneven and dot 

 it with circular spots, having no coating, while the other 

 causes it to wrinkle and crack. W nen tne g^ ass which is to 

 be platinized has been thus covered with the preparation, 

 and is sufficiently dry, it is placed with others in a muffle 

 furnace, and exposed to a heat almost sufficient to melt the 

 glass. This produces the necessary decomposition of the 

 platinum, the foreign substances are driven off, leaving the 

 metal burned into the surface of the glass and highly polished, 

 thus completing the operation. 



The advantages of this new method of constructing mirrors 



