TRANSACTIONS OF THK SECTIONS. 45 



Its atmospheric oxidation may possibly be expressed as follows : — 



C,H,(CH3)(C3H,)+Oe=CeH,(CH3)CO(OH)+CH3CO(OH)+H,0„ 



thus obtaining by limited oxidation a toluic and acetic acid and peroxide of 

 bydi'ogen. 



Wlien dilute nitric acid is employed as tlie oxidant toluic acid is formed ; and in 

 the case of stronger oxidants terephthalic acid is produced, the latter being a product 

 not formed by atmospheric oxidation. 



The production of peroxide of hydrogen from these bodies may possibly lead to 

 a modihcation of the views of the constitution of hydrocarbons now entertained. 



On tlie Treatment of Sewage. By J. C. Melliss. 



Some Remarks on Chiynoitic Acid, By A. Oppenheim. 



On Nodiluchie. By Dr. T. L. Phipson. 



On Apparatus and Modes of Examination for the Source of Polluted Air, 

 By "William Thomson, F.C.S. 



This paper has reference principally to the detection and relative determination 

 of the amount of hydrochloric and sulphmic acids issuing from chemical or other 

 works sm-rounded by works which are also said to pollute the air, to prove the 

 amount of pollution proceeding from any individual works. 



My first experiments were confined to litmus-paper, which I found would not act 

 well unless the papers were kept moist. To effect this I took bottles flattened on 

 both sides, having a small hole bored in the shoulder ; a piece of blotting-paper was 

 fixed on the front of the bottle by elastic bands, and kept quite wet by a piece of 

 cotton-wick passing thi'ough the small hole in the bottle, which was filled with pure 

 water : the litmus-paper was then moistened with water and laid on the wet blotting- 

 paper ; it may thus be kept moist for any length of time without washing any of 

 the litmus from the paper. If, then, several moist litmus-papers be kept at the 

 side of the works, in a direct line with the direction of the smoke, and another set of 

 papers placed at exactly the opposite side of the works, and both left for a few hom-s, 

 a comparison of the two sets of papers will give a fair idea of the amoxmt of acidity 

 emitted by the works by the difference in point of redness of the litmus. 



With the view to determine the actual amount of impm'ities put into the atmosphere 

 hy any individual works, I placed carbonic-acid bulbs, connected by means of india- 

 rubber tubing with an aspirator, and so arranged them that by means of a pulley they 

 could be raised or lowered through a range of about 30 feet on a j oiuted pole ; by this 

 means they could be placed as nearly as possible about the level at which the smoke and 

 other vapours passed : but as the wind changed often it was necessary for the experi- 

 ment that the pole, bulbs, and aspirators should be moved about in accordance with 

 the changes in the direction of the wind ; this was done by having the appliances 

 fixed on a vehicle. About 120 gallons of air were passed thi-ough 500 grains of water 

 alone and also made slightly alkaline with pm-e caustic soda, the apparatus being kept 

 always in the direct line of the smoke from the works ; and 120 gallons of air were 

 passed through other bulbs, the apparatus always being kept to exactly the oppo- 

 site side from that to which the smoke was blown. Thus I was enabled to get the 

 relative amount of impurities in the atmosphere immediately before and immediately 

 after it pa-ssed the works ; and as it took about twelve hours to pass this quantity 

 of air through each apparatus, it no doubt gave a fair estimate of the amount of 

 impurities emitted by the works. 



It is also advisable to corroborate these results by other means, such as collecting 

 rain-water from different directions near the works, at the same time observing the 

 direction of the wind during the time the rain is falling &c. 



On a new Gaseous Compound of Fluorine and Phosphorus. 

 By Professor T. E." Thorpe, F.CS. 



