INDUSTRIAL PROGRESS DURING THE YEAR 187G. Lxxix 



solutions in order to form platinum black ; 15 c, c. of glycerin of 

 specific gravity 25 to 27 Baume, and 10 c. c. potassium hydrate of 

 density 1.08, are gently heated, and 3 to 5 c. c. of platinic chloride 

 is added. The platinum black falls, and is collected and washed. 



Meyer has described a lecture experiment for illustrating that va- 

 porization without fusion is due to pressure. Two glass tubes contain- 

 ing iodine are prepared and sealed, one vacuous, the other at nearly 

 the ordinary pressure. If now both tubes be w^armed, the iodine in 

 the second tube melts, and may be made to run down the w^alls of 

 the tube ; in the vacuous tube the iodine only volatilizes. 



Landauer has proposed a very simple form of blow-pipe, which 

 consists simply of two bottles tubulated at bottom, and connected by 

 these tubulures through a rubber tube. The u^jper opening of one 

 of these is closed by a cork, through which a tube passes going to 

 the jet. This bottle being empty, the other bottle is filled with wa- 

 ter and i^laced at a convenient height. The hydrostatic pressure 

 forces the air out of the first and lower bottle through the jet. 



Frerichs has devised a new form of balance, in which the beam is 

 made of aluminum alloyed with five j^er cent, of silver. The beam 

 is very short, and yet the balance is not at all deficient in delicacy. 

 The use of riders is disjDcnsed with, the small weights being de- 

 termined by the torsion of a wire ingeniously arranged. 



Arzberger projDoses the use of an air-damping apparatus for chem- 

 ical balances, to diminish their oscillations. To the stirrup a gilded 

 brass plate is hung, which moves in a short cylinder, a trifle larger 

 in diameter, supported on the case. 



Drechsel has described a new form of wash-bottle, differing from 

 the older forms by having the tubes ground into the neck of the 

 flask, the delivery tube being enlarged for this purpose, while up 

 through the top of this enlarged stopper comes the inlet tube. For 

 washing with corrosive substances it may be useful. 



Mohr has communicated a paper on the nature and origin of me- 

 teorites, in which he discusses at length the chemical and astronom- 

 ical questions involved. 



Houzeau has proposed a method for the volumetric determination 

 of carbon dioxide, depending on the absorption of the gas by a grad- 

 uated solution of alkali, precipitation by barium chloride, and esti- 

 mation of the free alkali. 



Duprc has ^^roposed a modification in Dumas' method for the 

 determination of nitrogen in organic analysis, which consists in a 

 carbonic-gas ajDparatus by which the air and the nitrogen may be 

 removed, and a peculiarly constructed cylinder for receiving and 

 measuring the gas. 



Johnson has observed the formation of nitrites in the potash bulbs 

 when bodies containing nitrogen are burned, and as these absorb 

 oxygen and increase in weight, they may cause an error. 



