ACADEMY OF SCIENCES. 193 



There are numerous sources of the presence of this extraneous mat- 

 ter in the atmosphere. Volcanic eruptions have darkened the air 

 for miles. The speaker had often been puzzled to distinguish be- 

 tween clouds of vapor and clouds of smoke. During the past two 

 or three days the skj had been filled with clouds, which appeared 

 to be dense volumes of smoke. 



Regular Meeting, October 7th, 1871. 

 President in the Chair. 



Charles T. Yale was elected a resident member. 



Dr. Blake called attention to a donation of crystals of borate of 

 lime, by Mr. Mosheimer, formed artificially in purifying crude bo- 

 rax from Borax Lake. Dr. Cooper stated that it had been proved 

 that borax could be made much cheaper from the waters of this 

 lake than from the borate of lime beds of Nevada. 



Dr. Blake stated that, in a recent visit to the Geysers, he had 

 collected specimens of the algae found growing in the waters at dif- 

 ferent temperatures. 



The highest temperature in which he had found any living organism was in 

 the water of a spring, the temperature of which was 198 degrees. In this spring 

 only two forms of confervte were found ; one very delicate, hair-like form, re- 

 sembling the Hydrocrocis Bischoffii, but larger ; the other form was a filament 

 with globular enlargements at intervals. In a spring, the temperature of which 

 was 174 degrees, many oscillarice were found, which, by the interlacement of their 

 delicate fibres, formed a semi-gelatinous mass. But two forms of diatoms were 

 found in this spring, the most abundant being one with a rectangular silicious 

 skeleton. In a spring of the temperature of 134 degrees, layers of filamentous 

 green and red algce were freely formed as the water flowed over the rocks. 

 These layers consisted of oscillaria, and also contained the delicate Hydrocrocis 

 Bischoffii in large quantities. The only diatom found was apparently of the 

 same species as that contained in the 174 degrees spring. In the water in the 

 creek of Geyser Canon, the temperature of which was about 112 degrees, there 

 were large quantities of algae, forming layers often two or three inches thick, 

 covering the bottom of the pools. Under this was a deposit of black mud, 

 formed, most likely, by the sulphuret of iron discharged from the springs above. 

 In this deposit but two forms of diatoms could be detected, the same as found 

 in the 174 degrees spring. The Doctor observed, however, tliat these deposits 



