[ 337 "] 



Nu. 43. 



A MECHANICAL DEVICE FOR SEALING OFF RADIUM 

 EMANATION TUBES. 



By H. H. POOLE, Sc.D. 



(Read April 29. Printed July 3, 1924.) 



In the extraction and purification of radium emanation for therapeutic purposes 

 it is essential that the operator should be guarded against the dangerous effects 

 of excessive exposure to the radiations emitted. The problem which has hitherto 

 presented the greatest difficulty in this respect in the Irish. Radium Institute 

 is that of the protection of the operator's fingers during the division, by sealiag 

 off, of the long capillary tube, containing the emanation, into pieces, each about 

 1-5 em. long, suitable for insertion in serum needles. It is essential that each 

 seal should be absolutely reliable, and that there should be no enlargement of 

 the tube beyond the diameter of 085 mm., which is the maximum allowed by 

 the standard needle. As the process involves the simultaneous rotation and 

 drawing out of the tube, it is difficult to ensure satisfactory results if the parts 

 to be separated are held in forceps. Even the use of rubber gloves, or finger 

 stalls, renders the process so much more difficult that the time required for 

 the sealing off is considerably lengthened. As the division of the tube into 

 short lengths is carried out immediately after the emanation has been drawn 

 into it, so that the activity of the tubes is increasing every instant, this attempt 

 at protection is not of much use, so that the usual practice has hitherto been to 

 hold the tube in the bare fingers, and trust to speedy work. This method has 

 proved satisfactory, in so far as no serious damage has occurred to any operator 's 

 fingers, but the small ^ and y ray activity that soon appears in the tubes is 

 sufficient to cause an appreciable amount of temporary injury, so that the 

 apparatus, photographs of which are shown in figs. 1 and 2, has been constructed 

 to obviate all handling of the tubes during the sub-division. The apparatus has 

 been in continuous use for some weeks, and works extremely well. 



It is constructed chiefly of meccano parts, and the scale may be judged 

 from the fact that the holes in the metal strips which form the framework are 

 ^ inch apart, between centres. As may be seen from fig. 2, the device may be 

 described as a crude form of miniature lathe, with two collinear chucks, in 

 which the capillary tube may be held, rotated independently at the same speed. 

 Each chuck is allowed about 3 mm. end play in its bearings, so that the space 

 between their near ends may be anything between 75 mm. and 13-5 mm. They 

 are normally pressed apart by the two pivoted fingers and the wire spring seen 

 in the photographs, but may be locked in the "near" position by the cam seen 

 near the bottom of fig. 2. A swinging frame is suspended from the end of the 



SCIBNT. PKOC. R.D.S., VOL. XVII, NO. 43. 3 T 



