5068 Arachnida. 



specimens immersed in it became soft and spoiled in a few weeks : I 

 also used simple solutions of several salts, without success ; when by 

 accident I met with one, which, as far as I have tried it, seems to 

 answer admirably, viz., sulphate of magnesia or Epsom salts. A 

 strong solution of this salt happened to be upon the table one evening 

 in July, 1854, when I returned from a short excursion to the sea-side; 

 and having brought home, among other objects of natural history, a 

 small fish, the name of which was unknown to me, and which I had 

 not then time to examine, I immersed it in some of the solution of 

 salts, thinking it might preserve it for a few days, until I had more 

 leisure. It remained unnoticed in the fluid for two or three weeks, 

 and when removed was apparently as fresh as when placed in it, and 

 had undergone no change of colour. As it appeared to preserve the 

 fish so well, I determined to try the same fluid upon spiders, and the 

 result fully answered my expectations. I have now specimens, which 

 were put up in August, 1854, the colours and forms of which are as 

 perfect as they were on the day they were placed in the tubes. 



Though eighteen months can scarcely be considered long enough 

 to afford positive proof of the preservative action of this salt during a 

 very lengthened period, yet the experiment has so far succeeded that 

 I think it may fairly be laid before the public, and I hope other natu- 

 ralists may be induced to make trial of it. To insure the success of 

 this plan it is necessary that certain precautions be adopted. In the 

 first place, if the salt be simply dissolved in water, the solution de- 

 composes and becomes flaky and turbid in a short time : to obviate 

 this, it is necessary either to acidulate the fluid with a few drops of 

 sulphuric acid or to add to it a little spirits of wine. I have tried 

 both these plans, and give the preference to the latter, the acid I think 

 slightly injuring the colours of the specimens. In the second place, 

 if a recently captured spider (particularly a large-bellied one) be 

 placed at once in a small tube filled with the saline solution, the 

 juices of its body mixing with the fluid cause the latter to become 

 mouldy : I always, therefore, immerse the specimens in rectified 

 spirits of wine, for at least twenty-four hours, and then either wash 

 them quickly in a little water or let the spirit evaporate from the sur- 

 face before putting them up in the saline fluid. If this last precaution 

 be neglected the salt crystallizes on the surface of the spider, and the 

 liquid becomes turbid, which I account for by the rectified spirit 

 having such a strong affinity for the water that it absorbs it rapidly 

 from the layer of the solution which it first comes in contact with, 

 and the salt assumes the solid form. 



