﻿Dr. T. J. Buker o>i Breath Figures. 7G1 



could be detected. The plates were again put in contact and 

 left in vacuo £01* 2 days, and then it was found that a transfer 

 from A to B had occurred. Plate A still retained its power 

 of producing a breath figure. 



These secondary transfers afford further confirmation of 

 the view that the substance which modifies the glass surface 

 is volatile, and it is worthy of notice that the glass on which 

 the first transfer was obtained still retained its property of 

 yielding a breath figure. 



Permanent record of a transferred figure. 



When silver is deposited chemically on a glass sheet which 

 has received a transfer, the pattern is recorded precisely in 

 the same manner as the figure on the original flamed plate. 



Transfer produced hy heating the flamed plate. 



A flamed plate and a " cleaned " plate were held face to 

 face by clips, and the back of the flamed plate was heated 

 by a Bunsen flame until it was uncomfortably hot to the 

 touch. When cold the " cleaned " plate showed an excellent 

 transfer, and the flamed plate itself still gave a perfect 

 breath figure. The original flamed plate was now placed in 

 contact with another " cleaned " plate, and the process was 

 repeated. This resulted in a very clear transfer, but rather 

 fainter than the first, indicating that not all the volatile 

 matter had been expelled by the first heating. 



Experiments were then made with the plates slightly 

 separated, and transfers were obtained even when the 

 distance between them was fully 2 mm., but the outlines 

 of the figures were less distinct, probably owing to diffusion 

 of the volatile matter during its passage across the inter- 

 vening space. 



Temperature required to expel the volatile matter. 



The volatile matter is rapidly dissipated at 100° C, for it 

 was found impossible to obtain a transfer from a flamed plate 

 which had been heated in a steam-oven for J hour. In this 

 connexion Lord Ravleigh's observation that a breath figure 

 may be obtained on the inside of a test-tube by heating it 

 externally to redness may be recalled. Such a figure should 

 be incipable of transference because the high temperature 

 of the walls of the tube would have expelled any volatile 

 matter which may have been there. To test the point a flat 

 sheet of fused silica was held so that the tip of a small 

 blowpipe-flame impinged on the middle of one face until a 



