. 
A. H. Chester—Artificial Crystals of Gold. 29 
show the current of air by means of smoke, was of the form D, 
fig. 1. a 6, equalled 58, hf 22; fg 10. (b.) The glass resona- 
tors of the acoustic mill were of the form D. ab equals 84; A vf 
12; fq 3. The length of the arms from the middle of the 
glass caps to the middle of the resonator was 52 millimeters. 
The weight of the whole wheel was 23 grams. (c.) Paper 7 
nators of the acoustic mill, fig. 8, were of the form A, fig. 
ab equals 34; cd 50; hf 6: S9 9 millimeters. The jee a 
the arms was 65; the weight of the whole wheel 9 grams 
(3.) Kundt’s tube, : equals 105 millimeters. The glass reso- 
nators of the acoustic mill were of the form D, fig. 1. a6 equals 
24; h fe 2; fg 7; length of the arms 30 millimeters. 
It is a striking. fact that very small resonators may give a 
very deep note; with fork A, I used a glass resonator of the 
form D, fig. 1, in which a b equals 24; hf 14; and fg, 1 milli- 
meter. The volume was about ninety times less than that of 
the resonant box of the fork, to whose note the resonator was 
tuned. Notwithstanding its smallness it showed acoustic 
repulsion, 
Art. HL—On certain artificial erystals of ke and Gold 
Amalgam ; by ALBERT H, CHES 
In casting bars of pure ee. for the manufacture of foil, 
traces of erystallization may often be observed upon their 
upper surfaces, and sometimes dluetinet ———_- forms. These 
are sebsteusta onc teienyalan donee sligh tly raised, ay sera 
tea They d do not seem to be distorted or ‘hase « t all. 
either do the dendritic forms so common in nature ie = 
far easily obtained artificially, appear on the surface of 
precip piled ok suka. yor ‘alates balled ak a : 
‘ete is a well known process in the’ common operation of 
