CHEMISTRY. 191 



Carbonic Acid. Parts in a. million. 



Manchester ordinary weather, 403 



" where fields begin, 369 



London parks, 394 



" average of 68 determinations, 439 



" Metropolitan railway, 1,452 



Glasgow opener parts, 461 



" closer parts, 539 



Ammonia. The determinations of ammonia, free and albu- 

 minoid, have not been made with the absolute accuracy of the 

 oxygen and carbonic acid determinations, and for the present are 

 to be regarded as comparative. Some of the results were as fol- 

 lows, expressed in grains per ? cubic feet : 



Free Ammonia. Albuminoid Ammonia. 



Inellan, , 22.845 60.228 



London (average of 18), 26.785 65.936 



Glasgow (4), 34.169 133.264 



Manchester (10), 53.582 116.544 



Metropolitan Railway, 31.561 163.167 



A midden, 146.911 181.524 



Hydrochloric and Sulphuric Acids. The average of a number 

 of determinations in London, November, 1869, was 92.293 grains 

 hydrochloric acid per ? cubic feet of air to 729.695 grains sul- 

 phuric acid per equal amount of air (1,000,000 cubic feet is prob- 

 ably far from the correct amount) . A summary of comparative 

 results obtained in certain places is as follows, the relation being 

 to Blackpool taken as 100 : 



Hydrochloric Acid. Sulphuric Acid. 



Blackpool, 100 100 



Buxton, 247 345 



Dedsbury, 277 320 



London, 320 361 



Manchester, 369 549 



St. Helens, 516 468 



Metropolitan Railway, 974 1,554 



Examination of Rain. The results from the examination of 

 rain are similar to, although not identical with, those obtained by 

 washing the air. The results of a large number of determina- 

 tions are to be found in R. Angus Smith's Sixth Annual Report, 

 as Inspector under the Alkali Act. {See also Journal of Scottish 

 Meteorological Society, Jan., 1870.) 



Amount of Carbonic Acid in the Air of Boston, Mass. Deter- 

 minations of the amount of carbonic acid in the air in various 

 localities in the city of Boston, made by Mr. A. H. Pearson, 

 Assistant in the Chemical Laboratory of the Massachusetts Insti- 

 tute of Technology, showed that the average amount, in streets 

 and open places in the south-western part of the city, was 387 

 parts in a million, the amount varying from 257 to 500. In the 

 Public Garden the average amount was 301 parts, and on the 

 Back Bay lands, somewhat farther south, the average amount was 

 413 parts in a million. The highest amount found was 500, and 



