132 EIGIITil REPORT — 1838. 



amount at least to eight or ten cubic feet per minute in an atmosphere 

 at ordinary temperatures. 



2. That the amount of supply sliould increase greatly with the 

 temperature. In the House of Commons he had never given less than 

 thirty cubic feet for each individual when very crowded, and on one 

 occasion he had supplied sixty cubic feet for each member for three 

 weeks successively. 



3. That the same attention should be paid to the moisture in the air 

 as to the temperature, and that the hygrometer is as indispensable in 

 providing a proper atmosphere as the thermometer and anemometer : 

 5000 feet of moist surface were used at the House of Commons. 



4. That the air may be filtered from suspended impurities, and in 

 manj' local situations others may be separated with extreme facility. 



5. That from the pernicious effects of minute quantities of impuri- 

 ties acting for a long period, it is desirable in providing artificial light 

 to exclude hermetically from every apartment all the products of com- 

 bustion. 



On the Modns Operandi of Nitrate of Silver as a Caustic and Thera- 

 peiitic Affcnt. By Robert D. Thomson, M.D. 



When a solution of animal matter, (for example, a solution of what is 

 usually termed albumen, obtained from the eggs of birds,) is added to 

 a solution of nitrate of silver, white coagula are immediately preci- 

 pitated resembling chloride of silver, but differing on closer inspec- 

 tion, as under the microscope, considerably from the latter salt. When 

 the precipitation is inducetl in considerable quantity, the upper portion 

 of the deposit soon begins (o turn darker coloured, and gradually as- 

 sumes a brownish appearance. The lower portion of the ])reeipitate, 

 however, still retains its original aspect with the addition of bands of 

 dark matter, which traverse it in different directions. In addition to 

 this we observe, that it becomes matted together and has a stringy 

 consistence approaching to that observed in the incipient formation of 

 the mucous membrane. Having added an excess of animal matter to 

 the nitrate of silver solution, the author threw the precipitate on a filter 

 and washed it repeatedly with distilled water. On testing the liquid 

 with a solution of the animal matter no precipitation ensued, demon- 

 strating that nitrate of silver in its original form no longer existed in 

 the solution, but had been entirely removed, or at least its properties 

 obscured, in consequence of the addition of the animal matter. To de- 

 termine, however, M'hether any silver existed in the fluid, the latter was 

 evaporated on the sand bath. The solution gradually became dark- 

 coloured, and the evaporating basin in which the experiment was made 

 was coated at the upper surfiice of the fluid M'ith a brown deposit. On 

 the total evaporation of the solution, a brown glazed-looking matter 

 covered the bottom of the vessel, which, on exposure in the cold, gra- 

 dually absorbed moisture from the atmosphere, and was readily scraped 



