PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 737 



tious. Now, as marriages between near relations are by no means 

 in the ratio of one to twenty, nor are even, perhaps, as one to a 

 thousand to the marriages between persons not related, it follows 

 that the proportion of idiotic progeny is vastly greater in the 

 former than in the latter ease." 



In these instances most of the parents were intemperate or scro- 

 fulous ; some were both the one and the other. Of course, there 

 were other causes to increase chances of infirm offspring beside 

 that of intermarriage. 



"Then it should be considered that idiocy is only one form in 

 which nature manifests that she has been offended by such inter- 

 marriages. It is believed by some that blindness, deafness, imbe- 

 cility and other infirmities are more likely to be the lot of the 

 children of parents related by blood than of others. If so, and it 

 seems likely that it is, then the probability of unhealthy or infirm 

 issue from such marriages becomes fearfully great, and the exist- 

 ence of the law against them is made out as clearly as though it 

 were written on tables of stone." 



Japanese Alloys. 

 Raphel Pumpelly, Esq., obtained from the native workers of 

 metals in Japan information relating to the composition of some 

 of the alloys made by them, of which the following is a condensed 

 account : 



1. /Shakdo, an interesting alloy of copper, with from one to ten 

 per cent, of gold. It is used for a great variety of ornaments, as 

 sword guards, pipes, clasps, &c. After being polished, they are 

 boiled in a solution of sulphate of copper, alum and diacetate of 

 copper (verdigris), by which they receive a beautiful bluish- 

 black color. When only one or two per cent, of gold is used, a 

 rich bronze is produced. When pure copper is treated with the 

 above named solution, it presented the appearance of an enameled 

 surface, with a rich reddish tint ; and brass thus treated has a simi- 

 lar surface, with a darker shade. 



2. Gtn .ski hu ichi (" quarter silver ") consists of copper, with 

 from 30 to 50 per cent, of silver, and has a rich gray color. 



3. MaJcume consists of several alloys and metals, associated in 

 such a manner as to produce an ornamental effect. Beautiful 

 damask work is made by soldering together, one over the other, 

 30 or 40 sheets of gold, shakdo, silver, rose copper, and " quarter 

 silver ; " then cutting holes partly through the whole, after which 



[Am. Inst.] UU 



