376 Dr. J. Reade on a permanent Soap-bubble, 



novelty of experiment ; I therefore rest my claims principally 

 on that ground, and hope in this paper that the reader may find 

 that interesting subject simplified. The first account of the 

 colours produced by thin plates is to be found in Mr. Boyle's 

 works : " To show the chemist that colours may be made to 

 appear or vanish, where there is no accession or change either 

 of the sulphureous, the saline, or the mercurial principles of 

 bodies, he says that all chemical essential oils, as also good 

 spirits of wine, by shaking till they rise in bubbles, appear of 

 various colours, which immediately vanish when the bubbles 

 burst, so that a colourless liquor may be immediately made 

 to exhibit a variety of colours and lose them in a moment 

 without any change in its essential principles: he then men- 

 tions the colours that appear in soap-bubbles, and also in tur- 

 pentine. Me sometimes got glass blown so thin as to exhibit 

 similar colours." Here we may remark, that although Mr. 

 Boyle did not advance any theory from these experiments, 

 yet it is evident that he connected the production of colours 

 with the thinness of the substance, as appears from his en- 

 deavours to blow glass sufficiently thin. This suggestion in 

 all probability afterwards gave the idea to Dr. Hooke, and 

 finally to Sir Isaac Newton, who has, the merit of clothing 

 Hooke's suggestion in a mathematical dress, beautiful and 

 interesting in the extreme. 



Dr. Hooke was the next to investigate this subject; at a meet- 

 ing of the Royal Society, 7th March 1672, he promised to ex- 

 hibit at their next meeting something which had neither reflec- 

 tion nor refraction, and yet was diaphanous ; he then produced 

 a bubble of soap and water. It was no wonder that so curious 

 an experiment should excite the interest of one of the most 

 learned, liberal and scientific societies in Europe; they re- 

 quested him to bring an account of it in writing at their next 

 meeting. " By means of a glass pipe he blew several small 

 bubbles out of a mixture of soap and water, when it was ob- 

 servable that at first they appeared white and clear, but that 

 after some time the film growing thinner, there appeared upon 

 it all the colours of the rainbow, first a pale yellow, then 

 orange, red, purple, blue, green, with the same series of co- 

 lours repeated." Sir Isaac Newton's experiments as exhibited 

 in his Optics are so well known, that I shall not enumerate 

 them in this paper, merely remarking that his bubble was so 

 evanescent that it burst before he had time to make an 

 accurate examination. Melville of Edinburgh thought to 

 make a permanent soap film by means of freezing. This was 

 impossible. It occurred to me that by taking off the atmo- 



