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CHAPTER II. 



THK ( (»LORS OV THE STKAM JET, AS RELATED TO THE NUMBER OF NUCLEI IN REACTION. 



1. Pn-Iimiiuirt/. — After these preliminary experiments on the efficiency of 

 the jet, it seemed advisable to make a first attempt to find the relation of the color 

 (if the cloudy condensation to the degree of saturation of the ionized air producing 

 it. Qualitative e.xperiaients for this purpose are easily devised, but in the absence 

 of dii-ect knowledge of the nature of the condensational activity of phosphorus, 

 and of the behavior of the steam Jet in relation thereto, interpretation is necessarily 

 dilticult. Thus, for example, if the air currents passing over phosphorus are either 

 too swift or too slow they both give a colorless fiehl, as has already been instanced. 

 If the temperature is too low or too high, similar results appear: whether the 

 condensation is due to nuclei or to chemical or electrical reactions is not definitely 

 disposed of; etc. 



2. Apparatus. — The apj)aratus used in this work is given in figure 1. (7 is 

 the color tube provided with a lateral elbow, 6", open above and either side about 

 18 inches long. Into the top of this dips the i)hosphorus tube P, so that the 

 charged efflux may be carried down by the current in C. P has the usual form 

 as given in Chapter I, figure 9//, above. It is about 1 cm. in diameter and 2(> cm. 

 long, and contains phosphorus strips sti'etched along the axis. A definite volume 

 of air per second is passed through /' by aid of the aspirator train V, M. V \s, a 

 large flask of S litres capacity, grailuated on the side S. Water is added from or 

 removed to the bucket J/, which can be raised or lowered by the pulley p. The 

 air from V passes the stop-cock F, a pin valve of fine workmanship, and by 

 opening this more or less the color in 6' can be regulated to a nicety. A dessicator, 

 P, removes superfluous moistuie. I did not find this a])purtenance essential, 

 though it clearly must prolong the life of the ionizer in /-*. In this respect alone, 

 moi-eovei-, it is unailvisable to draw the air backwai'd, through the phosphorus 

 tube, into V. 



A seconds watch was at hand to measure the rate of influx of water into the 

 volumeter V, and therefore the rate of efflux of air out of V, through P, into 6" 

 and C. The ell)ow was supjiosed to insure mixture. 



This original apparatus has an obvious eri'or in design, since the pressure of 

 the air in K varies as J/ is more or less raised above the water level in I" Air 

 is at first introduced at slightly liigher jiressure and relatively greater volume than 

 at the end of the experiment. The effect on the color of the tube was not marked, 

 but it was thought best to obviate it as follows. Retaining V with the new cock 



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