Proceedings of the P olytechntc Association. 1007 



merely the old Hare or oxy-hydrogen light with zirconia substituted 

 for lime or magnesia. Zirconia has been used before for producing 

 light, and so have most of the earths, but the present improvement 

 consists in a better method of preparing the zirconia. Lime gives an 

 intense light when placed in the flame of the oxy-hydrogen blow-pipe, 

 but it crumbles away. Different specimens of lime are of different 

 values for this purpose. Some are almost worthless, while some good 

 pieces of lime will last for a long time. The lime from Glen's Falls 

 has been found to be the best in this country. But magnesia is bet- 

 ter than lime, and zirconia is still better than magnesia, as it not 

 only gives a very intense light, but it lasts a long time. 



Mr. John Phin. — The probability is that the quality of any pencil 

 of lime will depend upon two things. Its freedom from such foreign 

 substances as tend to render it fusible, and its freshness. If the pen- 

 cil is not freshly burned ; if it has become hydrated in the slightest 

 degree, it will fall to powder at the first touch of the oxy-hydrogen 

 flame. In luy experience, whenever the light begins to fail, I look 

 with confidence for evidences of fusion on the surface of the pencil. 

 It is well known that various substances, such as silica and some 

 alkalies and metals, render lime veiy fusible when tJiey are mixed 

 with it. 



A gentleman present, here asked if the new light could be made 

 so steady and so easily used tliat it would serve for ordinary purpo- 

 ses of illumination. 



Dr. P. Yanderweyde. — There is no diffculty in the matter if the 

 apparatus be in charge of a good chemist. The lime light can be 

 maintained for hours, if the gases are regularly supplied and the 

 apparatus properly attended to. But the ordinary attendants of 

 lighthouses, etc., are not chemists, and cannot manage the appar- 

 atus. 



Mr. T. D. Stetson, — It is strange that this light, invented by Dr. 

 Robert Hare of Philadelphia, should still be called the Drummond 

 light. This name was given to it by the English, who have not yet 

 found out that we Americans can do anything, and have not yet dis- 

 covered, or at least have not yet published in their books, that 

 Morse had anything to do with the telegraph, or Field anything to 

 do with the Atlantic cable. 



Mr. J. K. Fisher. — The lime light was discovered by Dr. Ilare, of 

 Pliiladelphia. Goldsworthy Gurney used it and called it the " Bude 

 light," and Lieutenant Drummond used it as a signal in the great 



