252 [November, 



AN IMPROVED ENTOMOLOGICAL PIN. 



BY H. GUARD KNAGGS, M.D., F.L.S., &c. 



Two opinions can hardly exist as to the inefficiency o£ the ento- 

 mological pins at present in use ; everybody grumbles about them. 

 The tinned and gilt sorts afford little or no security against the action 

 of insect fluids, while the enamelled kind are rough, and the temper 

 of the metal has been so deteriorated by the hot process to which it 

 has been subjected, that the points often turn on meeting with but 

 comparatively trifling resistance. 



For some months my attention has been directed towards in- 

 vestigating this matter, and after patient enquiry I have come to the 

 conclusion, that the primary cause of failure to satisfy our wants lies 

 in the metal itself, and in the innumerable imperfections in the wire 

 from which the pins are formed, these imperfections having been in- 

 creased by twisting in the act of " drawing," so that a surface is 

 presented which it is seemingly impossible to coat, whether with tin, 

 gold, silver, or nictel, with sufficient completeness to ensure the pro- 

 tection of the metal beneath. Such being the case, a radical change 

 in the original material would seem to be necessary in order to produce 

 an ideal pin. For this purpose nickel appears to be the best suited ; 

 it is as hard as iron, or nearly so, is ductile, and resists all acids ex- 

 cepting nitric, which it is not likely to meet with in its entomological 

 career.* My old friend, Mr. Charles Fenn, has suggested to me 

 aluminium, but though this is ductile, and resists all acids excepting 

 hydrochloric, it is, in its ordinary state, a soft metal, though it is said 

 that it may be made as hard as iron by hammering. I have not yet been 

 able to procure wire made from nickel or hammered aluminium, and 

 have not the run of a pin making machine, or I might write with 

 greater authority upon the subject. 



Still, though I almost despair of producing a perfect pin without 

 a change in the metal basis, it has seemed to me that considerable 

 improvement might be effected, in the way of remedying the defects 

 of the article already in use, and with this end in view I have lately 

 conducted a long series of experiments, with at any rate a moderate 

 amount of success. 



I will not weary your readers with an enumeration of my various 

 attempts to solve the problem, but will content myself with laying 

 before them one of the methods which appears to be as good as any, and 

 is certainly the cheapest and simplest. * First cleanse from grease and 

 other impurities some ordinary white entomological pins by soaking 

 them in a strong solution of washing soda or potash for not less than 



* Nickel pins are advertised by Deyrolle fils of Paris. -G. C. C. 



