IX. OZONOMETERS. 



715 



2905. Smyth's Ozouometer, for the determination of the 

 amount of ozone in a measured volume of air by means of an 

 aspirator, invented by the contributor and described by him in a 

 paper read at the meeting of the British Association in Birming- 

 ham in 1865. John Smytli^jun. 



It consists of a box-wood tube or cylindrical box, about two inches long 

 and two inches in diameter, one end of which is closed, except in the 

 centre, where it is pierced by a quarter-inch tube communicating with 

 the aspirator ; the open end is covered by a lid or second box of the same 

 material, which is so large as to slide over the first, and is also pierced by a 

 quarter-inch tube, which, when the ozonometer is arranged for an experi- 

 ment, directs the air against the centre of the test paper stretched across the 

 open end of the inner or first box, and is secured there by an india-rubber band 

 lyin<y in a groove. 



2905a. Schonbein's Ozonometer, rendered self-recording. 

 An instrument for exposing each hour a fresh piece of Schonbein's 

 ozone test-paper to the influence of the atmosphere. 



R. C. Cann Lippincott. 



Two c}4inders (one large, the other small) are enclosed in boxes, the openings 

 of which are guarded by india-rubber lips. The boxes are 2^ inches apart. 

 The large cylinder is moved round 2^ inches each hour by means of a driving- 

 shaft attached to the clock. A strip of test-paper, about 5 ft. long and of an 

 inch wide, is rolled round the small cylinder, the free end of it being fastened 

 to the large cylinder ; 2^ inches of paper are thus exposed to the influence of 

 the atmosphere. 



The clock, which goes 8 days, indicates the minutes only, and shifts the 

 paper by causing the large cylinder to rotate 2 inches of its circumference 

 exactly at the hour, thus removing the portion of paper (2|- inches long) 

 exposed during the past hour, and exposing a fresh portion, to be in its turn 

 removed at the end of another hour and succeeded by a new piece, and so on. 

 At the end of 24 hours the whole strip of test-paper is unrolled by the ob- 

 server from the large cylinder, dipped, and read by the scale (Schonbein's) ; 

 a fresh strip i.s then rolled round the small cylinder, and its free end is 

 attached to the large cylinder as before. 



The instrument was made for me by Mr. Casella, in 1868, after a plan of 

 my own suggestion. 



The following are the results of some observations made with the instrument 

 taken from the " Proceedings of the Meteorological Society," Vol. V., p. 51. 



MEAX HOURLY AMOUNTS of OZONE deduced from Observations taken every 

 Hour (with a few omissions when the clock stopped) from Feb. 20 to 

 Nov. 18, 1869. Test paper, Schonbein's; scale, to 10. 



