Si8 JVotices in JVaiural History. 



upon which other floating plants perish, affording by their decompo- 

 sition, an extremely fertile soil, increased from time to time by the 

 constant decay of other plants that spring up and grow in it ; so 

 that in the course of time, these islands, by a gradual augmentation 

 in extent and thickness, will in all probability, fill up and cover the 

 whole superficies of the lake with their artificial soil, and yield to fu- 

 ture ages a mine of inflammable turf which may supply an excel- 

 lent fuel for domestic uses. 



Upon these islands, which are called chivinas by the inhabitants, 

 great numbers of birds of many species deposit their eggs. Amongst 

 them are Swans, Flamingos, Herons and an infinity of others, many 

 of which are unknown to science. 



The geological formation to the north of the lake is basaltic, and 

 of the south granitic ; these are separated from each other by great 

 banks of phonoliie, of arkose, and of a very fine stone suitable for 

 whet-stones. The hill which contains it is called " el cerro de la 

 piedra de afilar," whet-stone hill. 



There is a great number of new and interesting specimens surround- 

 ing the lake. Amongst the new ones M. Gay enumerates two spe- 

 cies of Poranihus, one Ranunculus, an Utricularia, a beautiful 

 Gahezia, Chotanthera, and a number of arborescent Gyneterice. 



The next visit of the Professor was to that part of the Cordilleras 

 called Cauquenes. On this route along the river Cachapual and the 

 " rio de los cipreses," he met with more than a hundred species of 

 plants which were unknown to him. Along the Cauquenes he fol- 

 lowed for more than ten leagues a basaltic formation running in a 

 horizontal direction, and alternating with wacke, dolerite and a resin- 

 ous quartz. He made a chemical analysis of the w^aters of the hot 

 baths of Cauquenes which are visited annually by great numbers of 

 invalids from every part of Peru and Chile. The base of these wa- 

 ters he found to be a hydrochloraie of soda, although it has been 

 generally supposed heretofore, that they were indebted for their vir- 

 tues to sulphur, of which substance, M. Gay declares, they do not 

 contain a single atom. There are however sulphur baths in the 

 neighborhood. 



In another letter M. Gay describes his visit to the gold mines of 

 Yaquil, (the ore of which is simply auriferous pyrites,) and to the 

 plain of Colchagua. " Passing by the plain," says he, " we enjoyed 

 the curious spectacle which so often disappointed the hopes of the 

 French troops in Egypt, when suffering from thirst in a dry and 



