GeorgiQ Gold. 255 



bath, and it was so concentmteil as to be oily in its consistency. 

 The solution being more concentrated than was desired, it was di- 

 luted and allowed to stand on the sandbath, exposed to the air. In 

 a short time the undissolved tin was observed to be coated with crys- 

 tals of metallic tin. Some of the crystals were small and granular, 

 liaving many facets ; some were long acicular prisms ; and others 

 were in foliated plates and plumose, like the precipitated lead of the 

 arbor Saturni. One of the acicular crystals, of the diameter of a 

 horse hair, was mounted on the reflective goniometer. It had four 

 brilliant planes, giving distinct reflected images, and each face in- 

 clined to the adjacent ones at angles of 90^. The experiment of 

 crystallizing the tin was repeated many times with the same result, 

 using not only the spongy, but also the columnar grain tin. In the 

 latter, the acid developed a crystalline structure, and probably it is 

 owing to this crystalline structure, that tin emits a peculiar crackling 

 noise when bent. 



If the solution containing the crystals of tin be set aside, in a cool 

 place, for 24 hours, they redissolve. The concentrated solution, 

 when set aside until cool, and then diluted with \vater, will also ve- 

 getate, but the crystals form more slowly than when the hot solution 

 is diluted. The crystallization can be shown before a class in the 

 lecture room, and it is more beautiftd than that of the arbor Diance. 



The explanation of the crystallization of the tin seems to be, that 

 one portion of the protoxide of tin in solution gives its oxygen to 

 the other, forming a permuriate, while the metallic tin derived from 

 the decomposed protoxide separates, and its molecules having free- 

 dom of motion in the liquid, arrange themselves according to the 

 laws of crystallization. 



IV. Georgia Gold. 



The Gold analyzed was clipped from a gold piece, used as a coin 

 in the gold mining districts of the Southern states. This piece was 

 stamped, " Georgia Gold" — " Ten Dollars''' — Templcton, As- 

 saycr." These pieces are made of the native gold, refined in the 

 fire. 



The pieces weigh 249 grains, which is equal to the weight of fine 

 gold in an American eagle, coined prior to 1834. The specific grav- 

 ity is 19.46, at 51° F. The gold is not fine, but an alloy of gold 

 and silver, about 2^3 carats fine. Ammonia indicates a mere trace 



