377 



possess great power in preventing confervoicl growths in fluids. lu this 

 it uiuch resembles quinine, for which it is proposed as a substitute. 



Printbuj on cloth.— M. Vail (Comptes-reudus, June 10, 1872) proposes 

 a new method of printing on cloth. It is known that when a solution 

 of nitrate of silver is brought into contact with copper or zinc, silver in 

 the metallic form is precipitated in a very line state of division. If the 

 cloth to be printed be moistened with a weak solution of nitrate of silver 

 and impressed with clean-faced types of copper or zinc, and the fabric 

 immediately washed in soft water, a clear and sharply dehued impres- 

 sion will remain and will resist the action of acids, alkalies, or soaps. 

 The color of the impression may bo varied, according to the strength of 

 the solution, from a light gray to a deep black. 



Alumininm coins. — French authorities state that the government, on 

 the recommendation of a scientific commission, has ordered experiments 

 to be made on the propriety and practicability of substituting an alloy 

 of aluminium for the bronze now used in coins. Aluminium has many 

 properties which adapt it w^ll to the purpose of coinage, and some of 

 its alloys are very beautiful. 



Coolcing-utensils made of copper are lighter and more convenient than 

 those made of iron, but the poisonous character of all the compounds of 

 copper, liable to be formed in the use of such vessels, is a serious objec- 

 tion to them. Copper vessels may be rendered perfectly safe by coating 

 them in the following manner : Take twelve parts of fluor spar and as 

 much unburnt gypsum, and add one part of powdered borax. Fuse this 

 mixture in a crucible. Pour the fused mass out, and after it has cooled 

 grind it fine with water, so as to form a thin paste, with which the in- 

 side of the copper vessel is to be painted. After this the vessel is set 

 away in a warm place till the paint is dry. When it is thoroughly dry, 

 the vessels are baked in an oven till the coating is fused. On cooling, 

 the vessel will be found coated with a smooth, white, opaque enamel, 

 which adheres strongly to the copper and protects it from the action of 

 all the A'egetable acids. 



Nitrate of ammonia in respiration. — M. Struve, by a series of well- 

 conducted experiments, has detected nitrate of ammonia in the water 

 exhaled from healthy lungs in breathing. From this he concludes that 

 the nitrogen of the air we breathe is not entirely passive in the process 

 of respiration, as physiologists have heretofore supposed. 



Production of ozone in the air.- — A series of very interesting experi- 

 ments have been made at Kissingen which prove conclusively that ozone 

 is formed during the evaporation of watei". Great care v/as taken in 

 these experiments to avoid such tests as might mislead the experimenter 

 regarding the true character of the active principle formed. Led by the 

 light of these experiments, we must infer that the air on the ocean is 

 richer in ozone than the air of inland places. 'Observations made on the 

 island of Texel confirm this view. 



Paper lamp-shades. — Dr. Mirus (Polytcclinlsches Notizblatt) mentions 

 two cases in Jena and one in Frankfort where persons using green 

 glazed paper lamp-shades were poisoned by the arsenic of the coloring 

 matter. The heat of the lamp volatilized the arsenic, and rendered the 

 small quantity present very dangerous, lu rooms properly ventilated 

 green lamp-shades may be harmless, but in close room.s such shades 

 should be avoided. 



Non-infammahle fahrics. — Cotton or linen goods may be rendered 



