314 



PROCEEDINGS OF THE AMERICAN ACADEMY 



II. A saturated solution of oxalic acid in water was made as above ; 

 the crystals obtained were dried between sheets of paper, and a portion 

 of them allowed to remain for one half an hour over sulphuric acid, 

 and another portion for one hour. Solutions were made of these crys- 

 tals of the same strength as above, and 25 c. c. of baryta water tested 

 with the same results as before. 



III. A saturated solution of oxalic acid in hot water was allowed to 

 stand until nearly cold. The crystals thus obtained were rejected and 

 the mother-liquor allowed to stand until another crop of crystals had 

 deposited. These crystals were dried between sheets of paper and for 

 one half an hour over sulphuric acid, a solution made of them, and the 

 baryta water tested in the usual manner with a like result. 



IV. A saturated solution of oxalic acid in cold water was allowed 

 to remain over sulphuric acid, under a bell-glass, until a quantity of 

 crystals was deposited. These were rejected and the mother-liquor 

 returned to the bell-glass, and a second crop of crystals obtained, which 

 were dried, pulverized, and a solution made of them. The baryta 

 water was tested with this solution, the result obtained being the same 

 as above. 



The conclusion drawn from the above experiments was, that the ox- 

 alic acid employed in the regular analyses did not differ from that used in 

 these experiments, where the conditions under which the solutions were 

 obtained would not admit the presence of impurities in the oxalic acid. 



The results of these examinations of the air for carbonic acid are as 



follows : — 



I. — Outer air in Boston. 



