298 Royal Astronomical Society. 



and add it, along with 3 equivs. of lime, to 16 pounds of a so- 

 hition of bleaching powder of sp. gr. 1"08. Heat the mixture 

 gradually to 160° Fahr. and stir it frequently during five 

 hours. Pour off the clear liquid, add 16 pounds more of the 

 same solution, and continue the heat three hours longer. The 

 combination is obtained white with only a slight brown tinge. 

 It is quite insoluble in water, and when dried does not alter 

 in the air. Nitric acid, by dissolving the lime, leaves the 

 peroxide of a deep black colour, and therefore much deeper 

 than that obtained by any of the processes usually employed. 

 I have had no means of determining the proportion of lime 

 contained in this plumbate. With less than two equivalents 

 to one of oxide the compound is not white; and an excess of 

 lime cannot afterwards be dissolved away by an acid without 

 discolouring the salt. 



* ' I found it convenient in these experiments to prepare a 

 quantity of cream of lime, by dropping newly-burnt lime into 

 boiling water, stirring up, allowing the sand and the grosser 

 parts to subside, and pouring off the superstratum. When 

 this again had subsided for some time, the water was poured 

 away, and the cream of lime which remained corked up in 

 small bottles for use. By this means I had always at hand a 

 quick lime, whose equivalent I knew, free from sand and free 

 from carbonate. Marble, of course, answers the best for this 

 purpose. 



*^' Manganese, again, appears in the nitric acid which has been 

 eiiiployed to decompose the plumbate, in the state of a pink- 

 coloured hypermanganic acid. When this solution is poured 

 off and more water and nitric acid added to the peroxide that 

 is left, a small quantity of sulphate of manganese restores the 

 colour. Peroxide of lead, prepared by the same or by other 

 means, when dried, does DPt.yigld the. pink. jCplour without 

 the application of heat. Ux/oa sifJ ni BxiofJsviagrfo sn, ; 



XL VI I. Proceedifigs of Learned Societies. 



ROYAL ASTRONOMICAL SOCIETY. 

 [Continued from p. 226.] 



April 11, /^N the Longitude of Paramatta. By C. Rumker, Esq. 



1845. ^^ Communicated by Dr. Lee. 



The object of this communication is to show that the method 

 of determining the longitude by means of moon- culminating stars 

 can be extended to large meridional differences. The observations 

 of the moon and moon- culminating stars made at Paramatta are 

 compared with those made at Greenwich, Paris, Abo, and Konigs- 

 berg, and the results have proved satisfactory. The correction to 



