Ozonometers o/Drs. Schonbein and Moffat. 523 



The mean daily amount by Schonbein's was 1-70 ; by Moffat's 

 3-83. 



Such results are too plain to require any lengthened com- 

 ments on the relative value of the two ozonometers. 



There can no longer i*emain a doubt that the papers prepared 

 by Moffat's formula are more sensitive than those of Schonbein 

 in the ratio of 2'3 to 1"0. The advantages possessed by the 

 former have been proved by observations in other localities 

 besides Bedford. Mr. Glaisher, in his valuable report on the 

 " Meteorology of London and its relation to the Epidemic of 

 Cholera," has stated that " the papers prepared by Dr. Moffat 

 were more sensitive than those of Dr. Schonbein, and accord- 

 ingly indicated the presence of ozone when none was indicated 

 by those of Schonbein" (page 71). It appears clear, therefore, 

 that our first step to be taken in further observations on ozone 

 is to adopt without delay, and uniformly. Dr. Moffat's formula 

 for test-paper*. 



The next step must be, not to theorize on scanty data of 

 coincidences, but to extend, as widely as possible, the field of 

 observation, and carefully to record results. Our progress may 

 seem slow, but it is by such patient labours that the secrets of 

 nature's laboratory piust be disclosed. 



In conclusion, we would express a hope that meteorologists 

 who ha^^e not yet added the ozonometer to their observatories 

 will no longer delay to do so. It must be by the cooperation of 

 many that certain and great results vrill be attained. Each may 

 feel that he is doing little — that he is only collecting, from day 

 to day, a few grains of evidence. 



"Trahit quodcunque potest, atque addit acervo 



Quern stniit, " 



But slight exertions become important when regarded as con- 

 tijbutions to a great result. Thus we must go on from day to 

 day, from year to year ; and, by and bye, the properties of ozone 

 will be wrested, like other secrets, from nature. We shall then 

 be able to contrast the certainties known with the hints and 

 suspicions of our present stage of inquiry, even as now we may 

 contrast our certain knowledge of heat, of electricity, of magnet- 

 ism, of light, and of many chemical phsenomena, with the mere 

 forebodings of a period not yet very remote. 



Bedford, June 2nd, 1856. 



* As considerable care is required in the thorough saturation of the paper 

 with solution of iodide of ])otassium and starch, we would suggest to ob- 

 servers desirous of obtaining trustworthy results, that it uould be most 

 advisable to obtain the prepared paper from the accredited agcuts, Negrctti 

 and Zambra, Ilatton Garden, London. This may be done at a very reason* 

 able expense. 



2M2 



