46 I Fubruaiy, 



The most convenient way of using it is to have a gas or spirit stove on the table, 

 then set the saucepan half filled with water to boil ; a gas stove is better than 

 spirit, as when the water boils the flame can be regulated to keep it just " on the 

 boil." The insect to be relaxed should be held not too near the blowpipe, as the 

 force of the steam may be too strong, nor too far off, as the larger volume of steam 

 wets the wings ; any one trying it will soon find out the best position, distance, &c. 

 The time taken varies according to the age of the specimens, and method of killing ; 

 ammonia-killed specimens are much easier than those killed with cyanide. 



I was naturally much interested in reading of the successful use of " wood 

 naphtha," related {ante p. 21) by Dr. Knaggs, although I had at that time already 

 tested it for myself, the method having been expounded by Mr. Mutch on page 305 

 of the "Record" for 1894. 



I agree with Dr. Knaggs that it is a very good method of relaxing, but not that 

 it obviates the use of watery vapour. Insects {Lepidoptera, at any rate) cannot be 

 safely handled and set without all parts, toings, legs, Sfc, having been softened to a 

 certain extent, to attain which condition the specimens must be put into the relaxing 

 pot, and left a certain time, depending on their condition, age and size, before any 

 attempt be made to thoroughly relax them by the application of either " wood 

 naphtha" or "steam." 



Attempt to set a moth, for instance, a Geometer of the size of Boarmia repan- 

 data, which has simply had the wings loosened by " wood naphtha," and the almost 

 certain result will be splitting of wings, and breaking off of legs and antennae. 



The moths I have been relaxing and setting mentioned above are of various 

 sizes, from that of British Scoparice to the largest Sphinx, and the following, after 

 much experimenting, I find to be the best means of relaxing the different sizes : — 

 most specimens, such as Scoparice, the flimsiest Pyrales, and small GeometrcB, are 

 quite ready to set after being in the relaxing pot about twelve hours, and are un- 

 doubtedly more fit to handle and set, relaxed this way, than by any other method. 

 The relaxing pot I used is a very good one, procured for me by Dr. Sharp, It is a 

 round glass pot, about ten inches in diameter and five inches deep, covered with a 

 piece of plate glass ; there is a small hole a quarter of an inch in diameter drilled 

 in this cover, which is most necessary, as it allows the ingress of air, which prevents 

 the wings from becoming too wet. To the two inches of wet sand should be added 

 a few drops of carbolic acid, not too much, as I fancy it retards relaxation ; the finer 

 the sand the better, as it forms a solid bed for pinning the insects on to. Care should 

 be taken not to allow the wings to touch the wet sand. 



For all larger moths, any in fact that are not sufficiently relaxed in twelve 

 hours, steaming as described above, or the application of wood naphtha as in the 

 article by Dr. Knaggs already referred to, is advisable. I have not tried wood 

 naphtha on large hawk-moths, but about three minutes' steaming after twelve hours 

 in the relaxing pot renders them quite ready for setting. 



The chief thing I would urge is — consider no moth fit to repin and set unless 

 it has been relaxed in every part, which can only be done by using the relaxing pot ; 

 even when they have been finished off by steam or wood naphtha, return them to 

 the relaxing pot until you can set them, as a very few minutes is sufficient to dry 

 the wings and render them brittle. 



Cambridge: January 1th, 1895. 



