jVIE. g. goee oisr the peopeeties op electeo-deposited antimony. 327 
sequence of a small quantity of the deposited substance, which was not firmly deposited, 
falling ofi" in a state of powder to the bottom of the electrolyte. 
Further jp articular s respecting the first variety. 
110. Several experiments (of which the following is an example) were made to deter- 
mine the influence of speed of deposition upon the state of aggregation, &c. of the depo- 
sited metal. Five parts of pure oxychloride of antimony were dissolved in 20 parts of pure 
hydrochloric acid of sp. gr. 1'15, and the solution (contained in one vessel) electrolysed 
simultaneously by two separate cmuents from two smgle Smee’s elements, one of which 
contained plates 6 ‘3 times the size of the other, each charged with the same exciting 
liquid, \iz. 1 measure of acid to 18 of water: the antimony anode of the large battery 
possessed six times the amoimt of sm’face of that of the other, but the cathodes were 
of equal size. The speed of deposition by the small battery was 0*75 gr. per square 
inch per hour, and by the large one 3-22 grs., or 4-26 times the amount. The rapid 
deposit exhibited much scaly cohesive action (17.), but the slow one did not. The slow 
deposit consisted nearly wholly of grey crystalline metal, which did not possess the 
thermic power, whilst the rapid one was nearly wholly black and amorphous, and 
possessed the usual heating quality. Owing to the decline of the current, the deposit 
upon both sides of the slow one was at fii’st black and amorphous, and then became 
grey ; and that upon the back of the rapid one consisted of alternate layers, black, grey, 
and black, produced by variations of the electric current, by gradual decline, and addi- 
tions of acid. 
111. It is particularly worthy of notice, that whether the alteration of electric power 
was gradual, as by slow exhaustion of the battery liquid, or sudden, as upon the additions 
of acid, the change of aggregation and of chemical composition of the deposited metal 
was sudden in both cases, in accordance with that rigid distinction or want of gradation 
between the two varieties of deposit already noticed (3.). The cohesion between the 
alternate layers was much more feeble than between the parts of the layers themselves, 
and the layers could be readily separated by means of a knife ; the lines of junction were 
quite distinct and definite, although the layers were in perfect contact, and no films of 
depositing liquid appeared to be enclosed between them. These sudden changes of aggre- 
gation are particularly interesting. 
112. It appears from this and other similar experiments, that with a suitable liquid, 
&c., when the quantity of the electric current is small in relation to the amount of 
receiving surface, the deposited metal is grey and crystalline, and possesses no heating 
power ; and that when it is relatively large the metal is dark-coloured and amorphous, 
and has the peculiar thermic properties; other circumstances, such as high tempera- 
ture of the solution, or excess of acid (9. 10. 11.), will also produce grey metal. 
113. In several instances, when the active variety had been rapidly deposited, it was 
less bright and smooth, its colour was lighter, its fractured surface was coarse, and on 
2t2 
