234 ANNUAL OF SCIENTIFIC DISCOVERY. 



tion. The diminution of oxygen amounted sometimes to 68.35 in 

 10,000 volumes of air. On the other hand, the air of the plain of 

 Bogota sometimes presents an amount of carbonic acid far greater than 

 the atmosphere of the tierra-caliente. This difference may be explained 

 either by the existence of volcanoes, which are situated not far from 

 Bogota, or by the more or less active influence of the solar light. It 

 will be conceived, in fact, that, in the tierra-caliente, where the temper- 

 ature is very elevated, the decomposition of the carbonic acid, by the 

 green parts of vegetables, must be effected in a far more rapid manner 

 than on the high plain of Bogota, where the temperature is not higher 

 than from 57 to 64, Fah. It is, perhaps, allowable to suppose, on ob- 

 serving this enormous quantity of carbonic acid appear from time to 

 time in the atmosphere of the New World, and, considering the large 

 number of volcanoes which exist in the country, that a portion of the 

 carbonic acid of the air in other countries is due to them, and that 

 they thus contribute in part to nourish the vast and beautiful vegeta- 

 tion of the tropics. Comptes Rendus. 



ON A NEW METHOD OF DETERMINING THE QUANTITY OF HYGROMETRIC 



MOISTURE IN THE AIR. 



DR. ANDREWS, at the British Association, stated that he had found 

 on trial, that several powders, when well dried, would rapidly and com- 

 pletely take up the moisture of damp air passed through them, as effect- 

 ually as the fused chloride of calcium, which is too troublesome in the 

 making, preserving and using, for common use. For instance, he had 

 found that well dried oxide of manganese and a still more univer- 

 sally attainable substance, powdered alabaster, or sulphate of lime, as 

 dried and prepared by plasterers, or by those who make casts being 

 inclosed in a small siphon, a measured bulk of air passed through 

 either, at a very quick or at the slowest rate, would be so effectually 

 deprived of all its hygrometric moisture, that another siphon, filled with 

 coarser fragments of fused chloride of calcium, gained no weight sen- 

 sible to a balance which turned with the one-thousandth part of a grain ; 

 the measured portion of damp air being in succession drawn through 

 the siphon containing the alabaster and that containing the fused 

 chloride of calcium. 



ON THE ASSUMED EXISTENCE OF AMMONIA IN THE GENERAL ATMOSPHERE. 



To the proceedings of the American Association, New Haven, 1850, 

 a paper of great value on the above subject was communicated by Dr. 

 A. A. Hayes, of Boston. After presenting a summary of the evidence 

 supporting the assumed fact of the general existence of ammonia in 

 the atmosphere, Dr. Hayes draws the following conclusions : 



" 1st. That ammonia, in some form of combination, is always pres- 

 ent near the earth's surface. 2d. That no experiments have been as 

 yet published which prove its general presence in the mass of the 

 atmosphere. 



While pursuing inquiries in this connection," continues Dr. Hayes, 



tt 



