518 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



bromide of silver plates with a dye of coralline we get the 

 maximum of photographic action in the indigo and the yel- 

 low; and by using aniline green the maximum of activity 

 in the indigo and red. Again, Becquerel has dissolved cor- 

 alline in the iodized collodion film, and obtained similar re- 

 sults. The most remarkable action was observed in the case 

 of chlorophyl, by the use of which a spectrum image of great 

 length was obtained from the ultra violet to the green, with 

 a weaker impression from the green to the red. Continuing 

 these observations in connection with what has more recently 

 been published by Lockyer, we find every reason to announce, 

 as a probable law, that the optical observation of the bands 

 of any chemical show the active rays for that chemical; 

 and that therefore, by a proper selection of dyes, a sensitive 

 plate may be prepared especially adapted to any or to all 

 operations on the spectrum. 12 A, X., 282. 



IMPROVEMENT IN THE MANUFACTURE OF STUCCO. 



A stucco has recently been prepared as follows, under the 

 name of French or English cement, which becomes unusually 

 hard when slowly worked with water, and which, when mixed 

 with pigments, as lampblack, ochre, etc., after complete hard- 

 ening, can be polished to resemble marble : Gypsum, after 

 bavins: been calcined once, is immersed for a few minutes in 

 a 10 to 12 per cent, solution of alum. Chemical analysis 

 shows that the plaster thus prepared is exceedingly pure, 

 and contains but little alumina or potash. The alum has 

 been replaced very successfully by Landrin with water con- 

 taining 8 to 10 per cent, of sulphuric acid, by placing the 

 gypsum in it, after its first calcination, for a quarter of an 

 hour, and then recalcining it. All organic matter is thus 

 destroyed, and the plaster, besides being of most excellent 

 quality, is pure white. 8 C\ November 26, 1874, 422. 



RED MARKING-INK FOR CLOTHING. 



A red ink for marking clothes, which is not attacked by 

 soap, alkalies, or acids, is prepared by Welger as follows: 

 Enough finely pulverized cinnabar to form a moderately 

 thick liquid is very intimately mixed with egg -albumen, 

 previously diluted with an equal bulk of water, and beaten 

 to a froth, and filtered through fine linen. Marks formed 



