114 Mr. C. Tomlinson on the Motion of Camphor 



the discovery of the mineral Hayesite in Chile, as well as its 

 mode of occurrence and formation, placed this question, I believe, 

 beyond a doubt. 



The mineral alluded to is found in suspension in the waters 

 of the hot springs called the Bafios del Toro situated in the Cor- 

 dilleras of Coquimbo, and occurs in the form of beautiful snow- 

 white silky or feathery flakes, which ultimately subside and form 

 a light flaky sediment of this mineral in a perfectly pure state, 

 as shown by a qualitative analysis made upon a portion of the 

 same. 



The process of its formation is at once most simple and inter- 

 esting. The hot vapours, due, without doubt, to the proximity of 

 the neighbouring volcanoes of this chain of mountains, here 

 make their escape through channels or crevices which conduct 

 them into these springs of water previously highly charged with 

 carbonate of lime in solution, taken up by the water from the 

 decomposing lime felspars of the porphyries and porphyritic tuffs 

 (with intercalated limestones) and sandstones which here repre- 

 sent the upper oolitic period ; as might be expected, the boracic 

 acid gas contained in these vapours bubbling up through the cal- 

 careous waters combines directly with the lime, producing the 

 silky flakes of borate of lime (Hayesine) thus seen in course of 

 formation, whilst at the same time the liberated carbonic acid 

 escapes into the atmosphere. 



It is hardly possible to produce a more beautiful illustration of 

 the actual formation of a mineral body. The Hayesine found as an 

 incrustation in the Tuscan borax lagoons is, without doubt, the 

 product of an analogous chemical action. 



XIV. On the Motion of Camphor towards the Light. By Charles 

 Tomlinson, Lecturer on Physical Science, King's College 

 School, London. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



DR. DRAPER'S letter, contained in your last Number, has 

 surprised me not a little. On the strength of a question 

 put in 1840, as to whether the side of the jar nearest the sun 

 may not be the colder, he claims the merit of the theory advanced 

 by me in your Number for November last. 



Dr. Draper's question, put in 1840, was answered by him- 

 self in his quarto volume, ( On the Forces which produce the 

 Organization of Plants/ published at New York in 1844. At 

 page 124 of the Appendix he says, " It might be suggested 

 that when a vessel is exposed to the sun, that part of the glass 



