JOSEPH BLACK: HIS LIFE AND WORK 7*7 



is a chaos, consisting not only of elastick, but also of 

 unelastick air-particles, which in plenty float in it, as well 

 as the sulphureous, saline, watry, and earthy particles, 

 which are no ways capable of being thrown off into a 

 permanently elastick state, like those particles which 

 constitute true permanent air/ This was the current 

 belief as regards the nature of air. 



The cause which gave rise to Black's famous research is 

 a curious one. Sir Robert Walpole, as well as his brother 

 Horace, afterwards Lord Walpole, were troubled with the 

 stone. They imagined that they had received benefit 

 from a medicine invented by a Mrs. Joanna Stephens; 

 and through their influence she received five thousand 

 pounds for revealing the secret, which was published in 

 the London Gazette on the 19th June 1739. It was 

 described as follows : 



'My medicines are a Powder, a Decoction, and Pills. 

 The powder consists of Egg-shells 1 and Snails, 2 both 

 calcined. The decoction is made by boiling some Herbs 3 

 (together with a Ball, which consists of Soap, 4 Swines'- 

 Cresses, burnt to a Blackness, and Honey) in water. The 

 Pills consist of Snails calcined, Wild Carrot seeds, Burdock 

 seeds, Ashen Keys, Hips and Hawes, all burnt to a Black- 

 ness, Soap and Honey.' 



Dr. Cullen and his colleagues held opposing views as to 

 the efficacy of such quaint and caustic remedies ; and it 

 was with the object of discovering a ' milder alkali,' and 

 bringing it into the service of medicine, that Black began 



1 ' Egg-shells and Snails calcined in a crucible surrounded with coal for 

 8 hours. Then left in an earthenware pan to slake in a dry room for 2 

 months. The Shells thus become of a milder taste, and fall into powder.' 



2 ' Snails left in a crucible until they have done smoaking, then rubbed 

 up in a mortar. Take 6 parts of Egg-shell to 1 of Snail-powder. Snails 

 ought only to be prepared in May, June, July, and August.' 



3 ' Herbs of decoction : Green Chamomile, Sweet Fennel, Parsley, and 

 Burdock ; leaves or roots.' 



4 'Soap: Best Alicant Soap.' 



