1820.] P/tj/sical Science during the Year 1819. 86 



5. Mr. Garden has pointed out a very singular substance from 

 coal tar, which has at first sight some resemblance to sperma- 

 ceti. It is white, has an aromatic smell, and, when heated, 

 melts and sublimes in beautiful silky plates. It dissolves in 

 alcohol, and in fixed and volatile oils, and acetic acid ; but is 

 insoluble in water {Annols of PhiJosophy, xv. 74). From a few 

 trials which I was enabled to make upon this substance by the 

 kindness of a friend, I consider it as a compound of three atoms 

 carbon + two atoms hydrogen. It is, therefore, the same thing 

 as an atom of olefiant gas united to an atom of carbon. 



XI. Mineral Waters. 



1 . Boiling Spring in the Harbour of Milto. — I had an oppor- 

 tunity of analyzing a specimen of this water about a year and a 

 half ago. It has a strong saline taste, and its specific gravity is 

 1-0331. The saline constituents in 500 grs. of this water, deter- 

 mined in the way described in the Annals of Philosophy, xiv. 27, 

 are as follows : 



Common salt 20*924 



Muriate of lime 3-505 



Sulphate of soda 0*684 



25-113 



So that it contains about half a per cent, more of salt than sea 

 water does. 



2. Aluminous Chalybeate on the Coast of Sussex. — Mr. 

 Cooper examined a specimen of mineral water from the coast of 

 Sussex between Newhaven and Rottingdean. It flows from 

 chalk, and its temperature is uniformly 65° as it issues from the 

 earth. Its specific gravity is 1-076 ; so that it is greatly heavier 

 than the boiling spiing in the island ol' Milto. It is shghtly 

 acidulous, and has the taste of iroii. Mr. Cooper detected the 

 following substance in it : 



Oxide of iron, Lime, 



Alumina, Carbonic acid, 



Muriatic acid. Soda. 



Sulphuric acid, 



(See Annals of Philosophy, xiv. 148.) 



3. Sea Water. — We are indebted to Dr. Marcet for an exten- 

 sive set of experiments on sea water collected from different parts 

 of the ocean, and from various seas. Of this a full account has 

 been given so lately in the Annals of Philosophy, xv. p. 439, 

 that it seems only necessary to refer the reader thither for a view 

 of the details. I may mention, however, Dr. Wollaston's disco- 

 very of the presence of potash in sea water to a very small 

 amount. 



4. hake Oiirmia. — In the same paper. Dr. Marcet has given us 

 the analysis of the water of the Lake Ourmia, in Persia, situated 



