EXPERIMENTS Wmr IONIZED AIll 



37 



per second aud was deteiiiiiued by tlie time it takes the dust, suddenly injected into 

 one end of the tube, to show itself at the other end by coloring the steam jet. The 

 phosphorus emanation {V liters per minute) was introduced into tlu; current at dis- 

 tances 150 aud 1500 centims., respectively, from the jet, as the data show. The 

 table gives the series chronologically. The velocity is here com])uted from k — 

 (rv/2 (x^')) In ( P/ V'), where tlie volumes V aud P correspond to the tub.- 

 lengths X and x'. 



TABLE 3.— ABSORPTION OF PHOSPHORUS DUST IN TUBES. TIN DRAhN- 

 PIPE. DIAMETER s cm. / = 4 cm. d = 28°. 



These results have also been constructed in the chart, figure 3, on the same 

 scale as the other curves, the data selected being those showing the maximum effect 

 of length. In fact, they are liable to be very variable, as the colors for the long 

 tubes become dull and are unsuitable for shai'[) comparisons. One may state that 

 more dust is requii'ed for long than for shoi't tubes, but that the difference is a rela- 

 tively vanishing rpiantity and out of all proportion with the data for small tubes. 

 The difference between the present ami the preceding experiments with tubes is this, 

 that whereas in the latter case (small bore) the saturated air is conveyed in the un- 

 diluted condition through the tubes, in the case of wide tubes (5 cm.) the saturated 

 dust is necessarily diluted on being introduced into the tube having its own indepen- 

 dent current of air. The present series shows the remarkal)]e preservative tendency 

 of this operation of dilution aud points out a i-eason for tlie constancy of behavior 

 of the color tube itself, after the nuclei have once Ijeen captured. 



'Opaque at 150 cm. "Green-yellow at 1500 cm. 'At 150 cm., violet. 'Opaque at 750 cm. 



