442 Sir Henry Boscoe [June 1, 



all the detailed manipulation of the exact measurement and separation 

 of the various constituents of a sample of coal-gas, and pointing out 

 how the calculations are to be made. 



Many were the physical properties of gases which formed the 

 subject of Bunsen's investigation. He devised new methods of 

 attack ; he invented novel instruments for effecting his object, and 

 was then able to study with accuracy the phenomena of gaseous 

 diffusion and absorption. All these researches were masterpieces of 

 experimental skill and of accurate and pains-taking work. 



Of all Bunsen's useful and ingenious inventions, that of the gas- 

 burner which bears his name is the most widely known and valued. 

 There is scarcely a household or a manufactory where this little 

 lamp is not in daily use for one purpose or another. About its 

 discovery an interesting tale can be told. 



Some short time before the opening of the new laboratory in 1856, 

 the town of Heidelberg was for the first time lighted with gas, and 

 Bunsen had to consider what kind of gas-burner he would use for 

 laboratory purposes. Eeturning from my Easter vacation in London, 

 I brought back with me an Argand burner with copper chimney and 

 wire-gauze top, which was the form commonly used in English 

 laboratories at that time for working with a smokeless flame. This 

 arrangement did not please Bunsen in the very least ; the flame was 

 flickering, it was too large, and the gas was so much diluted with air 

 that the flame-temperature was greatly depressed. He would make a 

 burner in which the mixture of gas and air would burn at the top of 

 the tube without any gauze whatsoever, giving a steady, small and 

 hot, non-luminous flame under such conditions that it not only would 

 burn without striking down when the gas supply was turned on full, 

 but also when the supply was diminished until only a minute flame 

 was left. This was a difricult, some thought it an impossible problem 

 to solve ; but, after many fruitless attempts and many tedious trials, 

 he succeeded, and the " Bunsen burner " came to light. 



In this burner an important principle is involved. The mixture 

 of air and gas in the tube must never reach the point at which an 

 explosive mixture is produced, viz. one volume of gas to about ten 

 volumes of air, either when the supply of gas is full on or turned 

 nearly off. 



This can only be effected by varying the volume of the aspirated 

 air in proportion to that of the issuing gas, and this is done auto- 

 matically by variation in a zone of diminished pressure caused by the 

 flow of the issuing gas. This same principle is illustrated by 

 Faraday's well-known experiments with the two cards. 



The carbon-zinc battery (1841) which goes by his name is one of 

 Bunsen's best known discoveries. The carbon cylinders, which 

 replace the platinum of Grove, rendered this form of battery the 

 cheapest and most reliable source of electricity until the genius of 

 Faraday rendered the dynamo possible. It is interesting to remember 

 that as early as 1843 Bunsen foreshadowed the production of light 



