Polytechnic Association. 589 



Mr. Fisher repeated his belief that blue and yellow, whether pig- 

 ments or rajs, produce green, and that red and green produce a 

 neutral tint; and inquired if the eye could distinguish between a 

 pigment reflecting pure green rays and one reflecting blue and yellow 

 rays. 



Dr. Van der Weyde — No ; but the prism can doit, and the spectro- 

 scope can do it still better. 



III. New Method of Painting. 

 M. Violette, the inventor of a new method of painting, employs a 

 so-called pulverizator (a spray-producing instrument), for applying 

 liquid pigments and dyes to the surface of textile fabrics, paper, etc. 

 The colored liquid is projected in an impalpable spray and made to 

 fall to any desired depth on the objects to be painted or dyed. 



IV. PRESERVATION OF MEATS. 



E. Pelouze gives, in the Moniteur Scientifique, the following 

 description of his process : The meat or other animal substance, first 

 out into pieces of convenient size, is placed for some time in an 

 atmosphere of carbonic oxide gas, under pressure. After this treat- 

 ment, the material is dried in a current of dry, cold air, so as to 

 remove all traces of moisture from the substance ; it is then treated 

 with an antiseptic solution — either a concentrated brine or a solution 

 of saltpeter, or water with pure carbolic acid. Finally, it is packed 

 in hermetically sealed vessels. 



Y. The Force of Detonating Gaseous Mixtures. 



Dr. Berthelot has completed his investigations on the force of gun- 

 powder and other explosive substances, by presenting in the Moniteur 

 Scientifique a table of explosive mixtures, consisting of oxygen with 

 various gases and vapors, also the amount of heat and pressure pro- 

 duced by one kilogramme of each mixture. According to this review, 

 the maximum effect of each mixture varies only from one to two, 

 and is about equal for the several hydrocarbons and the vapors of 

 ether and benzine ; but this effect surpasses that of all solid, as well as 

 of all liquid, explosive compounds. With hydrogen and oxygen, for 

 instance, it is five times greater than that of powder, and two and one- 

 half times greater than that of nitro-glycerine. The gaseous mixtures 

 experimented with are supposed to be under atmospheric pressure. 

 The pressure theoretically exerted by them is between twenty and 

 forty-nine atmospheres, each at fifteen pounds pressure to the square 



