Page:Magic (Ellis Stanyon).djvu/161



.—Having had occasion several times during the course of the present work to make use of "flash paper," I will now describe the manner in which it is prepared. It is not, however, practical to manufacture it at home, as it can be obtained in large quantities at a very small cost.

A mixture of nitric and sulphuric acids, one part of the former to two of the latter, is made, and allowed to stand for twelve hours before using. The experiment should be made in the open air. Ordinary tissue paper is then immersed in the fluid for a few seconds, after which it is taken out and washed well in clear water, until all trace of the acid has been removed. This can be ascertained by the use of blue litmus paper, which when dipped into the water will betray the presence of the acid by turning red. The paper should then be dried in a warm atmosphere, but not near a fire, and it is ready for use.

Flash handkerchiefs are prepared in a similar Rh