Proceedings of the Polytechnic Association. 939 



partly as pectate of ammonia. This acid being weak, tlie alkaline 

 carbonates, when cold, act very feebly upon the fiber, but boiling 

 will transform the pectic into metapectic acid, and then the action of 

 the carbonates is as energetic as that of caustic alkalies, with this 

 advantage, the fiber is not weakened. Lime, even when cold, 

 impairs the strength of the fiber considerably, and boiling with 

 caustic soda is much more destructive. Having proved the existence 

 of pectose in unsteeped flax, and pectic acid in the same flax after 

 steeping, Kolb calls the attention of chemists to pectic fermentation, 

 doubtless before known to them, but now of high importance from 

 its industrial application. 



Antidote to Phosphorus. 



The fact that the vapor of turpentine prevents the ignition, and 

 even the phosphorescence of phosphorus, has been made of practical 

 use in a match factory at Stafibrd. The workmen who apply phos- 

 phorus to the matclies carry on the breast a tin cup containing tur- 

 pentine, and are thus protected from that dreadful disease of the 

 bones which sometimes attacks those who handle phosphorus. 



Spurious Gold Dust. 

 '^OY nearly two years past small parcels have been sent, from time 

 to time, to the United States mint in New York, for coinage, which 

 prove to be small flatfish grains of platinum, alloyed with copper and 

 silver, and sometimes coated with gold. Platinum being of greater 

 specific gravity tiian gold, enough of a lighter metal is added to give 

 the counterfeit the required weight. When coated with gold, the 

 grain must be boiled for an hour or more in a mixture of hydro- 

 chloric and nitric acids to remove the coating and expose the plati- 

 num. It is believed that this counterfeit is manufactured in France, 

 and sent through Mexico into the gold regions of this country. 



Electric Pyrometer. 



The method of measuring very delicate changes in temperature by 

 means of the thermo-electric current, generated when two difl'erent 

 ■ metals or alloys are united and exposed to such temperature, has been 

 modified by M. Bequerel so as to measure the highest eflfects of fire. 

 He takes two metals, which resist the action of all artificial heat, 

 except that of the hydro-oxygen blow-pipe, and forms a thermo- 

 electric couple, and to the galvanometer he attaches a graduated 



