1042 SEC. 19. EDUCATIONAL APPLIANCES. 



(6.) Apparatus for showing the action of oxygen upon nitric 

 acid. 



(7.) Apparatus for illustrating the absorption of gases by 

 liquids. 



(8.) Condenser for bromine and other coloured vapours. 



(9.) Apparatus for showing the formation of flowers of 

 sulphur. 



(10.) Apparatus for illustrating the manufacture of sulphuric 

 acid, and for showing the decolorising action of sulphurous acid 

 upon nitric peroxide. 



4114. Photographs, illustrative of the chemical lecture-room 

 of the Polytechnic School of Aix-la-Chapelle, and of the contri- 

 vances for throwing experimental illustrations on a screen by means 

 of a Dtiboscq's lamp. P r f- & Landolt, Aix-la-Chapelle. 



4115. Photographs of the lecture-room table, showing the 

 provisions made for enabling the audience to see more favourably 

 any experimental demonstration, by employing screens behind the 

 lecture-table. Prof. H. Landolt, Aix-la-Chapelle. 



APPARATUS FOR TEACHING MINERALOGY. 



4116. " Student's Elementary Collection of Minerals." 



J. R. Gregory. 



4117. Elementary Collections (four) of Minerals, Fossils, 

 and Rocks, systematically arranged, in polished wood cabinets ; 

 fitted for the use of the student and science-class teacher, and 

 illustrating the various mineralogical and geological handbooks. 



Thomas J. Downing. 



4118. Minerals (24) for Blowpipe Analysis. In case, 

 for the pocket. Set I. Thomas J. Downing. 



4119. Minerals (24) for Blowpipe Analysis. In case, 

 for the pocket. Set II. Thomas J. Downing. 



4127. Apparatus for demonstrating the physical properties 

 of Steam and the Steam-jet. 



Dr. L. Bleekrode, The Hague, Holland. 



This apparatus is designed for the lecture-table, and consists in a copper 

 boiler, which is heated by a common gas-burner with six or seven flames. 

 The quantity of water it contains is sufficient to perform all the experiments 

 during an hour, so that it needs no feeding, and the strength of the material 

 permits the production of steam at a pressure of four to five atmospheres. 



The following experiments may successively be taken or illustrated one 

 after another : 



I. The principle of the water-gauge in a boiler. 

 II. The action of the safety-valve. 





