CHEMICAL SCIENCE. 261 



and perpetuating -works of the highest artistic character, and which may 

 be executed on a vast scale. Fuchs' method is as follows : Clean and 

 washed quartz-sand is mixed with the smallest quantity of lime which will 

 enable the plasterer to place it on the wall. The surface is then taken off 

 with an iron-scraper, in order to remove the layer formed in contact with the 

 atmosphere, the wall being still moist during the operation. The wall is 

 then allowed to dry ; after drying, it is just in the state in which it could 

 be rubbed off with the finger. The wall has now to be fixed, i. e., moist- 

 ened with water-glass. (An important point is, not to use too much 

 water-glass in moistening the wall.) This operation is usually performed 

 with a brush. The wall must be left in such a condition as to be capable 

 of receiving colors when afterwards painted on. If, as frequently happens, 

 the wall has been too strongly fixed, the surface has to be removed with 

 pumice, and to be fixed again. Being fixed in this manner, the wall is 

 suffered to dry. Before the painter begins, he moistens the part on which 

 he purposes to work with distilled water, squirted on by a syringe. He 

 then paints : if he wishes to repaint any part, he moistens again. As soon 

 as the picture is finished, it is syringed over with water-glass. After the 

 wall is dry, the syringing is continued as long as a wet sponge can remove 

 any of the color. An efflorescence of carbonate of soda sometimes appears 

 on the picture soon after its completion. This may either be removed by 

 syringing with water, or maybe left to the action of the atmosphere. Not 

 to dwell on the obvious advantages possessed by the stereochrome over 

 the real fresco, (such as its admitting of being retouched and its dispensing 

 with joinings,) it appears that damp and atmospheric influences, notori- 

 ously destructive of real fres'co, do not injure pictures executed by this 

 process. The following crucial experiment was made on one of these pic- 

 tures. It was suspended for twelve months in the open air, under the 

 principal chimney of the New Museum at Berlin; "during that time it 

 was exposed to sunshine, mist, snow, and rain," and nevertheless " re- 

 tained its full brilliancy of color." 



IODINE AS AN ANTIDOTE FOR POISONS. 



M. Bernard established some time ago that the solutions of iodine act as 

 antidotes against the bite of venomous serpents, and especially of the 

 crotales. He has recently communicated another note (framed conjointly 

 with M. Greene) to the Academy of Sciences, to state that the same solu- 

 tions of iodine have a similar influence on the South American poisons 

 called curare. Their experiments support the opinion long currently be- 

 lieved, that the poison of serpents is an ingredient of these poisons, which 

 have two effects analogous to those of the bites of the most dangerous ser- 

 pents. The curare is so very active that a dose of two or three centigrammes 

 proves fatal to an animal of the size of a pigeon or a guinea pig ; but when 

 this poison was mixed with a solution of iodine or iodurated pot assium, it 

 may be injected under the skin without danger. The poison may even be 



