Real and supposed effects of igneous action. 345 



Silica and alumine, in very small quantities. 



Carbonic acid gas, - . - . 304 cubic inches 



Atmospheric air, - - . . 5 



Gaseous contents in a gallon, - - 309 



Specific gravity oF the water at the temperature of 60° is 

 1006.85, pure water being 1000,*" and its temperature at the 

 bottom of the rock is uniformly 48° Fahr. 



Art. XXI. — Real and supposed effects of igneous action. 



l.-Letters from the Sandwich Islands ; by Joseph Goodrich. 

 n. — A letter from Mexico ; hy William Maclure. 



I. Mr. Goodrich's Letters. 

 Remarks. 



In a note to an account of the volcanic character of the 

 island of Hawaii, published in Vol. XI. of this Journal, men- 

 tion is made of a box of minerals destined for the Editor. — 

 They Having arrived, we shall annex to the extracts, from a let- 

 ter preceding and another accompanying them, such remarks 

 as may serve to explain the characteristic appearances of the 

 specimens. The first letter is dated Byron's Bay, Hawaii, Oct. 

 25, 1 828. The writer says : — " I embrace this opportunity of 

 sending you a small cask of minerals, of my own collecting. 

 They are chiefly from the great volcano, an account of which I 

 gave you in a letter of ! 825 ;t the crater is not so deep now 

 as it was then, by three hundred, or four hundred feet, the la- 

 va having boiled up from beneath. I have been there sever- 

 al times since I formerly wrote to you. I can easily perceive 

 that great alterations are taking place at the bottom ; it is 

 fillmg up gradually, and slight shocks of earthquakes occur 

 here frequently. 



The minerals that are at the upper part of the cask, I col- 

 lected upon the summit of MounaKea. Some of them appear 

 to me to be fragments of the granite rock. The shells that 

 are with them, the largest^ is from the Gulf of California ; the 

 remainder are from this island. The volcanic specimens in 



* The sp. gr. of the Hamilton spring water (left hlank, p. 245) is, as we 

 since learn, 1008.5, pure water being 1000. — Ed. 



t Which is published in Vol. XI. p. 2. \ A magnificent pearl oyster. 

 Vol. XVI.— No. 2. 17 



