Proceedings of tee Polytechnic Association. 937 



important modification of the winnowing system, or some very great 

 advances toward perfection therein. Tlie jets of air thrown up 

 tln-ongh tlie bed of material in rapid succession have the eifect to 

 shake the light to the top and the heavy to the bottom, almost irre- 

 spective of the varying sizes of the grains. 



Decorative "Wall Painting. 

 Dr. Isador Walz presented specimens of the oleo-chromo decora- 

 tive wall painting, the invention of Messrs. Cousin, Owry, and 

 Washauer, of France. This method of decorating walls, &c., is 

 intended to supersede the usual mode of frescoing and wall paper- 

 ing. The colors are printed on the paper, resembling somewhat the 

 paper used by lithograpliers in transferring; the paper is then 

 evenly pressed against the wall, and left there for a few hours, when 

 it is moistened v*'ith water ; it is then peeled off the wall when the 

 beautiful oil colors are left behind. The paper tlius taken off can be 

 used again after recoloring. The size used for preparing the paper 

 is made of camphor, lime, Cayenne pepper, and water. This method 

 of coloring walls, &c., can be made as cheap as the common mode 

 of papering. Mr. Washauer exhibited the manner of putting the 

 colors on articles by covering boards, sheets of tin, &c. 



Steam Engines. 



Mr. C. E. Emery read the report of the judges for the late fair of 

 the Institute upon steam engines, which occupied the remainder of 

 the evening. 



In this connection it may be of interest to state that this was not the 

 first practical test made by the American Institute of steam engines 

 on exhibition at its annual fairs. One previous test, which elicited 

 many points of interest to the engineering profession, was made in 

 the Crystal Palace in 1858, on two engines which had remained in 

 the building from the American Institute exhibition of 1857. An 

 official report was made to the Institute, which never appeared in its 

 Transactions, it having been, probably, destroyed during the burning 

 of the Crystal Palace in 1858. The premiums were never awarded 

 on that test, but a minute and interesting description of the experi- 

 ments, with their incompleteness and the reasons therefor, was pub- 

 lished in the IS'ovember and December numbers of the Practical 

 Mechanics' Journal of London, for 185S, and has never, so far as 

 knov.'n, been before printed in this country. It is from the pen of 



