Mr. A. H. Churcli un the Spheroidal State of Bodies. "^77 



of feri'ocyanide of potassium floating upon a solution of sesqui- 

 chloride of irou, while not a trace of Prussian blue is formed. 

 These experiments must of course be recommenced whenever 

 any union of the liquids employed has taken place. The cork 

 spoken of above should have two perforations, one to admit the 

 funnel-tube, and the other to allow the escape of air. 



Is the employment of a volatile substance essential to the pro- 

 duction of these pha^nomena? I imagined that this question 

 might be answered by the following experiment. A dish of pla- 

 tinum might be heated strongly, and a drop of melted lead then 

 placed upon it ; now if the production of vapour from the sub- 

 stances employed were essential to the formation of the sphe- 

 roidal state, the lead should at once dissolve and perforate the 

 platinum; if, however, the spheroidal state occurs when two 

 non-volatile substances are employed, the platinum vessel should 

 not be perforated until its temperature has been considerably 

 reduced. The experiment was tried with every precaution to 

 prevent the oxidation of the lead and ensure an accurate result ; 

 a perforation of the platinum ensued the moment of placing the 

 melted lead upon it. This proves that the production of vapour 

 is essential to the occurrence of the spheroidal state ; for it can- 

 not be urged that that condition is never manifested when metals 

 only are employed; for a drop of a volatile metal, mercury 

 (melted mercury, we may say, in order to render its relationship 

 to melted lead the more apparent), placed on an intensely heated 

 surface of platinum instantly assumes the spheroidal form, and 

 evaporating slowly, dances about in the vessel with peculiar 

 movements. Upon thin, sonorous vessels of copper, &c., this 

 movement takes place with such rapidity as to produce a musical 

 tone of high pitch. I have sometimes seen globules of mercury 

 and water rise to the height of six inches from the capsules in 

 which they had been formed. 



A word or two in conclusion, as an attempt at an explanation 

 of the pheenomena observed may not be out out of place. 



Since a space always exists between the lower body and that 

 in the spheroidal state, and since that state is not manifested by 

 non-volatile substances, it seems reasonable to conclude that the 

 vapour proceeding from those parts of the liquids nearest to the 

 containing vessel or subjacent fluid tends to assist the internal 

 molecular cohesive force of the drops in assuming and maiutain- 

 ing their spheroidal foru). Other forces originated by the tem- 

 perature may also be in operation. 



1 should premise that the solution of sulphide of sodium 

 employed in my first experiment made a dark stain upon silver 

 even in the cold. This renders the nulHty of its action at a high 

 temperature the more remarkable. It will be scarcely necessary 



