Aluminium. 189 



sulphuret of gold, and hyposulphite of silver containing excess 

 of sulphurous acid, have, however, been employed with tolerable 

 success for these purposes. Other processes have been found to 

 answer better, but their details are not known. Plates of cop- 

 per or brass, and aluminium, strongly pressed together at a 

 dark red heat, will uuite ; if it is attempted to treat gold and 

 aluminium in the same way, the temperature required for cohe- 

 sion will cause the two metals to combine. In depositing me- 

 tals on aluminium, by means of the galvanic battery, we must 

 not use acid solutions in which hydrochloric acid, or combined 

 chlorine is present ; nor must alkaline solutions of the metals — 

 so useful in other cases, be employed. Pure aluminium may 

 be easily coated with copper, by a bath of sulphate of copper. 

 A patent was taken out some time ago, for plating with alu- 

 minium. The solution used was obtained by dissolving alum 

 in water, adding ammonia as long as any alumina was thrown 

 down ; then filtering, adding distilled water, boiling with cya- 

 nide of potassium, and filtering when cold. And the article 

 to be coated was suspended in it, by copper or brass rods con- 

 nected with the zinc pole of a battery ; a bag of alumina, or a 

 piece of platina, being connected with the other pole. 



It is difficult to solder aluminium, on account of our not 

 knowing a flux that cleanses without altering it, or protects the 

 solder without acting upon it; and a thoroughly strong joint has 

 not yet been made in this way, although various methods have 

 been adopted. Some persons deposit copper on the surfaces, 

 and then apply the solder to unite them. With the process of 

 M. Mourey, which is probably the best that has yet been used, 

 the surfaces to be united are smeared over with a mixture of tur- 

 pentine, balsam of copaiba, and lemon juice; they are then 

 placed on hot coals, and the flame of a gas lamp, or of a self- 

 acting blowpipe, is directed between them ; after which, small 

 pieces of an alloy containing six parts aluminium and ninety- 

 four parts zinc, are placed in contact with them, and, when 

 melted, are pressed upon them with tools made of aluminium. 

 The surfaces thus coated, are next brought close together, and 

 kept so by wires ; after which, an alloy containing twenty parts 

 aluminium and eighty parts zinc, is applied, in bits, to the 

 points in contact outside, and is melted in with a lamp. When 

 cold, the article bears filing and re -working. 



We have now brought under the notice of the reader, almost 

 everything of importance yet known regarding this interesting 

 metal : and we do this the more willingly, because its general 

 adoption is assuredly but a question of time. This must be 

 greatly shortened, through the labours of ingenious and per- 

 severing experimentalists, who may be induced to give their 

 attention to the subject, by the reasonable expectation of bene- 



