4 A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



cooled, or othenvise treated. The following diagram, figure i, will make the 

 adjustments clear. 



Figure i. — Apparatus for Comparint, Nucleation and Ionization. A. Coronal Chamber; R, 

 Exhaustion Reservoir; M, Mariotte Flask; C, Tubular Condenser; P (to be Inserted in the Con- 

 veyance Tube, e). Phosphorus Ionizer; G and C, Vacuum Gauges; F, Cotton Filter; B, Storage 

 Battery Terminals. Tube p to Suction Pump, a to Atmosphere, c and c' for Exhaustion, e for 

 Conveying Nuclei into Condenser, d for Filtration, h from the Hydrant. Supports g, g, are 

 Metallic, i, i. Insulating. 



The parts of the train of apparatus are the large copper Mariotte flask M, 

 with a supply of water sufficient for aspiration, the condensation chamber A, 

 used both for producing coronas and for the aspiration and storage of air laden 

 with phosphorus nuclei, the exhaustion chamber, R, the phosphorus ionizer, 

 P, the tubular electrical condenser, C, and the electrometer, E. An accessory 

 desiccator, D, of the tower form may be inserted on the way, when dry air is 

 needed, as shown in figure 2. 



R is connected through a stopcock with the suction pump at p, with the 

 atmosphere at a, and by wide tubing with the condensation chamber, A. It 

 carries a vacumii gauge, G. 



A is connected with a stopcock with the cotton filter, F, with the ionizer 

 by b (where the tall desiccator may be inserted), with R by c, and also carries a 

 vacuum gauge, G' . A is fiu'ther joined by stopcocks with the Mariotte flask, 

 M, for aspiration, and is graduated in liters on its side. It holds about 10 

 liters. 



The ionizer, P, is a large U tube containing calcic chloride for desiccation, 

 kept in place by loose cotton plugs. One shank is nearly empty, and at g 

 carries thin pellets of phosphorus between strips of wire gauze. 



The condenser is tubular, 2.10 and .64 cm. in diameter and 50 cm. long, 

 with the outer mantel permanently put to earth. The core is a brass rod, sup- 



