XXVI. 



Proceedings. [May 18th, 1920 



sometimes assumes a laminated structure exhibiting an irides- 

 cent effect resembling Mother-of-Pearl. When this oxide dries 

 it becomes dull white and loses its iridescence. 



When exposed to air, amalgamated aluminium foil gives 

 rise to growths ; but these seldom assume fine feathery shapes 

 unless the degree of the humidity of the air be suitable. They 

 usually occur as very copious dense growths ; and a striking 

 effect is obtained by writing on aluminium foil with Nessler's 

 solution and allowing the growth to develop ; when it finally 

 forms white tufts along the lines of the letters. 



It is very remarkable that no such growths could be obtained 

 from amalgamated magnesium although this metal undergoes 

 oxidation more readily than aluminium at the ordinary tem- 

 perature of the air. 



" Further Notes on Aluminium Amalgam." 18th May, 

 1920, by the same authors. 



On the 3rd of February last we showed examples of the 

 delicate white filaments which grew out from aluminium wire 

 which had previously been rubbed with metallic mercury or 

 otherwise amalgamated. 



These filaments we found to contain mercury and we deter- 

 mined the quantity present in some of the growths from wires 

 amalgamated in different ways. 



With a view to find whether the mercury associated with the 

 alumina which constituted these growths was a definite quantity 

 relative to the alumina, we submitted them to analysis and 

 herewith we give the composition of the growths in six different 

 experiments. 



Percentage. 



Composition of Filamentous Growths from Aluminium Wire 

 Amalgamated with Nessler's Solution from which the excess of 

 Mercury and liquor was :• — 









Wiped 



off and 



Not wiped, 

 but washed 









the wire then 



with alcohol 





Wiped off with 

 a. 



a cloth. 

 b. 



passed through 

 dry mercury. 



and then 

 with ether. 



Mercury 



Hygroscopic water 

 (dried over strong 



4.55 



4.54 



70.8 



67.5 



20.21 

 75.4 



sulphuric acid) 



5.14 ^ 











Water (lost at 100 °C.) 

 „ ( „ red heat) 

 Alumina (A1 2 3 ) 



16.17 I 30.71 

 9.40 ) 



64.74 



31.82 

 63.64^ 



29.2 



32.5 



*61.30 



24.6 18.49 





100.00 



100.00 



100.0 



100.0 100.0 100.00 



* The cooling effect of the ether treatment probably had the effect of 

 condensing an excessive quantity of water on to the wire. 



