476 SEC. 13. CHEMISTKY. 



No. 48, a glass lens, wrapped in a piece of paper, labelled iu Dalton's 

 writing, " Sun's focus 4-2 inches." 



No. 49 is a paper containing " 10th of grains," made by Dr. Dalton of iron 

 wire. The paper in which these are wrapped is part of a note from one of 

 Dr. Dalton's pupils (as is well known, he lived by teaching mathematics at 

 half-a-crown per lesson), in which the writer presents his " complements to 

 " Mr. Dalton, and is sorry that he will not be able to wait upon him to-day, 

 " as he is going to Liverpool with a few friends who are trying the railway 

 " for the first time. Mr. D. may fully expect him on Monday at the usual 

 " time." 



No. 50 are bottles of tin, earthenware, and silver, some of them being 

 common penny pot ink bottles. Each has a thermometer tube cemented into 

 the neck of the bottle, and these tubes are provided with paper scales. These 

 were used by Dalton probably for experiments on radiant heat 



No. 51 is a manometer tube used by Dalton ; it consists of a tin vessel 

 attached on either side to leaden tubing, and having a thermometer-tube 

 closed at the upper end, and provided with a divided scale, fixed into the 

 upper portion of the tin vessel. 



No. 52, Dalton's Balance, made by Accum, and capable of arrangement as 

 hydrostatic-balance with weights and counterpoises. 



2398. Balance used by Cavendish. 



The Royal Institution of Great Britain. 



This balance, of rude exterior but singular perfection, was made by Harri- 

 son according to the plan and by order of Henry Cavendish, Esq., and passed 

 at his death to his cousin and heir, Lord George Cavendish. By him it was 

 presented to Sir Humphry Davy, together with the greater part of Mr. 

 Cavendish's philosophical apparatus. Presented to the Royal Institution of 

 Great Britain by Mr. Felix R. Garden. 



2399. Balance used by Dr. Thomas Young and Sir 



Humphry Davy. The Royal Institution of Great Britain. 



A balance made by Fidler for the Royal Institution, nearly resembling 

 those of Ramsden and Troughton. " Lectures on Natural Philosophy," by 

 Thomas Young, M.D., 1807. " Works of Sir Humphery Davy," vol. 5, 

 page 17. 



2400. Balance used by Sir Humphry Davy. Presented to 

 Professor Roscoe by Mrs. F. Crace-Calvert. 



Professor Roscoe, F.R.S. 



2401. Balance used in his experiments by Dr. Joseph Black, 

 Professor of Chemistry in the University of Edinburgh, from 

 1766 to 1799. Dr. Black was the discoverer of fixed air (carbonic 

 acid), and author of the theory of latent heat. 



Edinburgh Museum of Science and Art. 



24Ola. Balance used by, or formerly belonging to, Dr. 

 Priestley. William Sykes Ward. 



This is remarkable as a good specimen of early work, having friction pulleys 

 for suspending the beam ; also an interchangeable piece with steel planes, 

 gearing for raising the beam concealed in foot, extra pans and glass bucket 

 for taking specific gravities. The successive owners of the balance are believed 

 to have been : Dr. Priestley (Leeds), Abraham Sharpe (Bradford), Joshua 

 Muff (Leeds), and the Exhibitor. 



