OF THE DEPENDENT ISLES OF TAIWAN. 45 



magnetite, apatite, together with the olivine had then sunk down, 

 and, formed the heap of cri/stals at the bottom, meanwhile the un- 

 consolidated residuum of the magma ivas actually slowly flowing 

 through the sieves of crystal-heap, or changed its chemical com- 

 position through diffusion, after the manner of liquation as 

 ill a metallurgical process. And, then, the solution having the 

 composition of the hydrous alumino-sodiura-silicate has finally 

 crystallised out in the interspaces of the meshes of crystals. 

 Similar process can 'oe frequently observed during the formation 

 of crystals on the stage of the microscope. If this be the actual 

 condition under which the Analcime- Basalts have consolidated, 

 considerable leaching and percolation must have taken place 

 during the formation of rocks, and the structure of such a rock 

 should better be called the ' leached.' This structure is therefore 

 properly seen only either in the granitic or in the granulitic 

 rock, consequently it is wanting in the family which has 

 a fluxional arrangement of the components. 



The Analcime-Basalts are represented in my collection by 

 three specimens from Gio-o, and one from Hoko, The hand- 

 specimen from Nai-an^^ in Gio-ô, is, according to Y. Saito, said to 

 occur at the water's edge, the main portion of the flow usually lies 

 under the level of sea, and constitutes the third sheet of lavas, 

 and is the loivest, consequently the oldest of the accessible lava- 

 flows of Gio-o. 



Other Analcime-Basalts of the Hoko Group no doubt belong 

 to the same horizon. 



1) Nai-an ^^, ^^^%. 



