NEUTRON EFFECTS ON ANIMALS 



47 



of the first plane Avould intersect the circumference. A length of copper 

 tubing was embedded along the axis of the form, to serve as specimen 

 holder. Samples placed at intervals along the portion of this tube within 

 the cylinder were thus protected in one direction by a wedge of wax varying 

 from to 5 inches in thickness, while all other directions were guarded 

 by at least 5 inches of paraffin. The chart accompanying the diagram in 

 Figure 1 indicates readings obtained by placing the chamber of a Victoreen 



Fig. 1. Ionization yradient in wax form. The wedge-shaped portion is 5 incbe.s 

 long, and 5 inches high. The circles indicate the points (one inch apart) at which 

 readings were taken with the 100 r meter, and the X's on the graph, the corresponding 

 values in terms of n units per integron division. Without the wax shielding the same 

 procedure would have given a value of 0.85 n in the same positions. 



100 r meter at the points within the specimen tube indicated by circles. 

 The values are expressed as n units per integron division (3). 



It is interesting to note that readings in air — i.e., without wax shielding 

 — in nearly the same location were invariably in the neighborhood of 0.85 n 

 per integron division. The fact that all readings within the form were 

 greater than 1 indicates the increase in ionization obtained from the neu- 

 trons when this large volume of wax was used. 



In other experiments, smaller spherical forms were used, and the n 



