BAIRD &TATLOCK. (LONDON) LTD. 



1768 



1770 



A 1772 



1771 



1768 U Pocket Balance, in French polished mahogany box, for a charge up to 10 grammes in 

 each pan, sensible to 2 milligrammes. With set of weights 5 grammes down to 2 milli- 

 grammes . . . . . . . . . . . . . . . . .. 



1769 U Pocket Balance, same as above, for a charge up to 100 grammes in each pan, and sensible 

 to 5 milligrammes. With set of weights 50 grammes down to 5 milligrammes . . . . 



1770" Lever Balances, to weigh 50 grammes 



1771" Lever Balance, with silver-plated scale, graduated to grammes 

 To carry . . . . . . . . . . 100 



Price .. .. ..8/6 



each, 1/2; per doz. 



250 grammes. 

 10/6 each. 



1772' Diamond Balance, in French polished mahogany box, can be charged up to 64 carats in 

 each pan, sensible to ^ carat, with its full charge. With set of weights 64 carats down 

 to T ' T carat . . . . . . . . . . ' 



M772" Micro-Balance, as devised by Prof. Dr. W. Nernst 



DESCRIPTION OF BALANCE. 



A very fine quartz thread about 5 centimetres long is placed horizontally between the prongs ot a brass fork 

 supported vertically on a pillar 16 centimetres high. Crosswise on it rests the capillary glass, 30 centimetres long, 

 0.5 millimetres diameter, which constitutes the balance beam ; this is fixed, by means of sodium silicate, to the 

 quartz thread. On the shorter arm of lever, which is about 9 centimetres long, a platinum hook is fused ; on this 

 the pan can be suspended. The long arm of lever is bent downwards at right angles, and tapers into a very fine 

 thread, over a graduated glass scale, which is divided into 0.5 millimetres. By observing through a telescope 

 under a good light, fa of each division is discernible. A brass fork is fitted to act as a support. On the left arm 

 of the balance a platinum cursor is attached by means of sodium silicate ; this is to counterpoise the scale pan. 

 This form of cursor has been devised to afford the required stability to the balance, without reducing its delicacy 

 more than is desirable for the measurement to be effected. The small platinum pan weighs, including the sus- 

 pension thread about 20 milligrammes. For weighing small crystals or for weights, a disc is supplied ; this is made 

 of platinum foil 0.8 centimetres diameter by 0.015 millimetres thick ; for decimal weighings a small capsule is 

 used of the same thickness as the round plate. The balance is supplied in a glass case, mounted on slate sole, 

 fitted with three thumbscrews. By regulating these screws one can easily adjust the balance on the zero point. 

 The balance is designed to weigh up to 2 milligrammes, sensitiveness ,-^5 to rfas part of a milligramme. 

 Each balance is supplied with directions showing how to mount same ready for use. 



109 



1 6 

 13 





 



120 

 750 



