844 Transactions of the American Institute. 



mother of pearl cards. 

 The sale of these beautiful visiting cards has becu forbidden by 

 the municipal authorities of Munich, it having been shown by 

 chemical analj^sis that they contain a soluble salt of lead, which, 

 being poisonous and sweet, would be dangerous in the hands of 

 children. 



RECOVERING INDIGO FROM RAGS. 



A French inventor's process consists in placing rags in a boiler 

 provided with a double bottom, and saturating them Avith a solu- 

 tion of caustic soda of the strength indicated by one degree Baume. 

 The rags are then subjected to the action of steam at forty-five 

 pounds pressure to reduce and dissolve the indigo, which is after- 

 ward precipitated from the soda solution and collected in a pure 

 state. 



IODINE AND PHENIC ACID. 



Dr. Percy Boulton has removed the objection to the external 

 application of a solution of iodine as a cure, on account of the dis- 

 coloration of the skin, by adding to it a few drops of carbolic or 

 phenic acid, one of the most efficient disinfecting agents now known. 

 This mixture is not quite colorless, and is said to be a sovereign 

 remedy for the sore throat, abscess in the ear, and similar painful 

 diseases. Dr. Boulton's recipe is as follows: Compound tincture 

 of iodine, 3 grammes; pure liquid carbolic (phenic) acid, 6 drops; 

 glycerine, 30 grammes; distilled water, 150 grammes. 



PONDERABLE MATTER THE ONLY 3IEDIUM OF ELECTRICITY. 



Mr. Alvergniat, of Paris, has constructed a new apparatus for 

 proving that electricity cannot pass through an absolute vacuum. 

 Two platinum wires are inserted into a tube so that their free ends 

 are within about an eighth of an inch of each other. The air is 

 then exhausted from the tulje by means of a mercurial column, after 

 which the electric spark will not pass from one platinum wire to 

 the other. 



DEATH FROM MARSH GAS. 



Dr. B. W. Richardson, has made some experiments with light 

 carl)uretted hydrogen, known among miners as fire-damp, to ascer- 

 tain what percentage in air would be fatal to the animal breathing 

 it. He found that pigeons could live about half an hour in air con- 

 taining thirty-five per cent of that gas. The diminution of circula- 

 tion and respiration was so gradual that it was difficult to 

 determine the exact time when death ensued. 



