1892.] 



connected with Cloudy Condensation. 



437 



made to tlie instrument for estimating more accurately the depth of 

 colour than can be done mentally. This might be done either by 

 means of coloured glasses of different depths for comparison, or in 

 some other way. 



A few comparative observations have been made with the koniscope 

 and the dust counter in the impure air of a room. While the num- 

 ber of particles was counted by means of the dust counter, the depth 

 of blue given by the koniscope was noted. A metal tube was fitted 

 up vertically in the room in such a way that it could be raised to 

 any desired height into the impure air near the ceiling so that sup- 

 plies of air of different degrees of impurity might be obtained. 

 To produce the impurity, the gas was lit and kept burning during 

 the experiments. The air was drawn down through the pipe by 

 means of the air-pump of the koniscope, and it passed through 

 the measuring apparatus of the dust counter on its way to the koni- 

 scope. The indications of the two instruments were taken, and are 

 entered in the following table : — 



Dust Counter. Koniscope. 

 Particles per c.c. Depth of colour. 



50,000 Colour just visible. 



80,000 Very pale blue. ' 



500,000 Pale blue. 



1,500,000 Fine blue. 



2,500,000 Deep blue. 



4,000,000 Very deep blue. 



It is probable that the higher numbers are too low, as the measure 

 of the dust counter has a capacity of only 10 c.mm. With so small 

 a measure it is probable that a good many of the particles are lost. 



When making a sanitary inspection, the air outside, or wherever the 

 supply was drawn from, would be tested first, and the depth of colour 

 which it gave would be noted. Any increase from that depth would 

 indicate that the air was being polluted, and the amount of increase in 

 the depth of colour would indicate the amount of increase of pollution. 

 Slight colour can be traced though the number of particles be less than 

 80,000 per c.c, but the colour is not very decided, the condensation 

 producing principally a darkening effect. It should be noted that 

 the above table refers to a koniscope with a test-tube 50 cm. long. 

 An instrument with a tube 1 metre long would be doubly sensitive, 

 and would show colour with fewer particles. 



It is thought that the koniscope will be useful for sanitary inspec- 

 tors, for investigating questions of ventilation in rooms lighted with 

 gas, and for other purposes. As an. illustration of what this instru- 

 ment can tell us, the following experiment may be given. It shows 

 us how we can trace by means of it the pollution taking place in our 



