508 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of tannin ; third, a solution of the chameleon mineral or per- 

 manganate of potash ; and, fourth, a solution of oxalic acid. 

 18 (7, August 2, 495. 



CAEBOLIC ACID FOE RUBBER HOSE. 



An important addition to the many practical applications 

 of carbolic acid has lately been made in the United States by 

 using it in the preparation of rubber hose. It is well known 

 that the durability of this article, where hemp or other vege- 

 table fibre is used as a basis, is greatly impaired by the tend- 

 ency to rot ; and a patent has lately been taken out, and is 

 being worked with much success, as we are informed, by 

 which the introduction of carbolic acid during the process 

 imparts much greater durability to the manufactured article. 

 Scientific JReview, February 1, 30. 



PLATINIZED MIEEOES. 



Much interest has been excited by the new method of con- 

 structing mirrors, invented by Dode, of France, in which the 

 chloride of platinum is used as a basis. For this purpose the 

 glass plate, after being cleaned, is set upright, and the metal- 

 lizing liquid applied with a brush, first from above downward, 

 then from right to left, and so on alternately until a perfectly 

 uniform coating is laid on. The platinizing liquid is prepared 

 by dissolving one thousand five hundred and fifty grains of 

 very thin rolled platinum in aqua regia, and carefully evapo- 

 rating the solution obtained in a sand-bath, and drying, so as 

 to prevent the chloride of platinum from becoming decom- 

 posed. It is then spread out upon a glass muller, and recti- 

 fied oil of lavender added, little by little, with continued rub- 

 bing. Care must be taken not to add the oil too quickly, as 

 otherwise too great an increase of temperature may result, 

 and thus destroy the preparation. After the addition of 

 about fourteen times as much oil of lavender as of the plati- 

 num used, the mixture is to be placed in a porcelain dish, and 

 allowed to remain perfectly quiet for fourteen days, after 

 which the liquid is to be poured off and filtered. After six 

 days more of rest the liquid is to be decanted, and should 

 then show five degrees upon the acid gauge of Beaume. To 

 the quantity of platinum just mentioned about four hundred 

 grains of litharge and as much of borate of lead are to be 



