156 Gr.-duc. Standardizing Institute for Glass Instruments, Ilmenau (Thur.). 



3. Muencke's and Dr. Norblad's Gas Generating Apparatus. 



4. Apparatus for the estimation of nitrogen in urine. 



5. Broegger-Harada's Apparatus for separating minerals con- 

 tained in heavy solutions (with large cock of 15 to 20 mm bore). 



6. Mercury Air Pump, own construction (small size). 



This pump excels over other pumps in the following respects: 



a. It works conveniently and is reliable. By repeatedly lifting 

 and lowering the mercury vessel successive evacuations are 

 obtained without the necessity of alternate^ opening and 

 closing cocks. A valve in the mercury pressure vessel pro- 

 tects the puihp from being broken in the event of careless 

 lifting ; 



b. The Dehydrating Apparatus is simple in its construction. It 

 is to be charged with anhydrous phosphoric acid and consists 

 of a simple bulb, which is ground to fit directly into the 

 shell of the cock, so that it may be taken off without ne- 

 cessitating the removal of any other part of the pump. The 

 cock is so constructed that one turn disconnects the dehy- 

 drating apparatus, so that the pump may also be used without 

 the latter. The pump has the further advantage that it may 

 be safely and easily packed for transport as it is composed 

 of small separate parts. 



7. Various Appliances, a Collection of Glass-cocks (exact re- 

 productions of Geissler's cocks), samples of Glass tubing, Beakers and 

 Boiling flasks. 



VI. H. R. Lindenlaub, Schmiedefeld in Thuringia. 



Glass-blowing and Glass Instrument Works; manufactures 

 Thermometers, Hydrometers and Glass Appliances of any kind 

 and excels in the manufacture of Radiometers and Geissler's Tubes. 



Exhibits : 



1. Geissler's Tubes. 



2. Eadiometers of various kinds, Radiometers registering the 

 number of rotations. 



VII. Strasser & Rhode, Glashiitte nr. Dresden. 



Clock and Watch Works. 

 Exhibits : 



1. Micrometer Gauge with short callipers, suitable for accu- 

 rately calibrating carbon filaments for incandescent lamps, glass- 

 tubes etc.; 



2. Micrometer Gauge with long callipers, which may be con- 

 veniently used in mechanical work -shops and glass-blowing 

 establishments. 



