Proceedings of Learned Societies. 305 



lias caused death in forty hcairs. Mr. Crookes, on the other hand, 

 denies its power, and states that he has occasionally swallowed a 

 few grains of its salts without injurious effect. 



Mr. Crookes' further researches on Thallium have brought for- 

 ward several points of great interest. In testing for thallium in the 

 flue-dust of pyrite burners, he finds that the spectrum analysis is 

 useless from its extreme delicacy ; ^ - part of thallium in a mass 

 being indicated as strongly and vividly as the pure metal itself. 



Mr. Crookes has been experimentingupon several tons of this dust. 

 The most ready method of extraction he finds to consist in washing 

 it with pure water, accidulating the liquid with .hydrochloric acid, 

 so as to convert the thallium into chloride. In this manner he has 

 obtained from three tons of flue-dust sixty-eight pounds of impure 

 chloride, which was afterwards converted into sulphate by heating 

 with sulphuric acid ; this conversion into chloride and reconversion 

 into sulphate being repeated, in order to get rid of impurities. 

 Finally, the sulphate was reduced to the metallic state by fusing 

 with blax flux or with cyanide of potassium. Thallium melts at 

 550° Fahr., and can consequently be easily fused over a gas jet, its 

 surface being protected from the air by a stream of coal-gas. 



Mr. Crookes exhibited a mass weighing upwards of a quarter of 

 a hundredweight, and demonstrated its more obvious properties. It 

 is the softest of the non-alkaline metals, being easily scratched by a 

 point of lead. When obtained in larger quantity, thallium will 

 doubtless be employed to furnish a magnificent green flame. Eight 

 parts of chlorate of thallium, two of calomel, and one of resin yields 

 a splendid light on being ignited, and a very little reduction in price 

 would enable it to be used for ship-signals ; its extraordinary inten- 

 sity and monochromatic character enabling it to penetrate through a 

 hazy atmosphere, which alters altogether the colour of the ordinary 

 green lights produced by the salts of baryta. 



SOCIAL SCIENCE CONG-RESS. 



Alleged Elevation op the Coast Line of the Lothians. — On 

 the occasion of the members of the Social Science Congress visiting 

 the Bass Rock, in the Firth of Forth, Mr. Bryson described the 

 geology of the district, particularly with reference to the alleged rise 

 of the coast line of the Lothians — one of the circumstances from 

 which Sir Charles Lyell has adduced an argument in support of his 

 views on the antiquity of man. Mr. Bryson maintained that no vio- 

 lent upheaval had taken place, but that the deposit on the shores of 

 the Firth had been caused by a great wave of translation, which had 

 thrown up the various marine remains that are now to be found far 

 elevated above the water line along the coast. 



ENTOMOLOGICAL SOCIETY.— Oct. 5. 



Destructive Habits op Larvje op Noctua segetum. — The im- 

 portance of study of practical entomology was evidenced by Mr. S. 



