Britton.] 1»^"^ [Dec. 3, 



percent. Jupiter's deviation is about 2.6 per cent. ; Saturn's, 1.2 per cent.; 

 Uranus's, 1 per cent. ; Earth's, i of 1 per cent. The co-efflcient-products 

 in the three principal planetary pairs are, 9 ©, i X § = 5 = nodal division 

 of linear pendulum; % I7 , § x t = 7. nearly = 2 r -f- kinetic radius; 

 § ^Z, I X f = 1- It seems probable that the actual determining orbit was 

 an ellipse, the two foci being within the masses of Sun and a Centauri, but 

 the difference between parabolic and elliptical co-ordinates in our planetary 

 system, is not recognizable so near the focus. 



Improved Mounted Burettes for Volumetric Analysis. 



By J. Blodget Britton. 



(Abstract of remarks made before the American Philosophical Society, De- 

 cember Zd, 1875.) 



More than a year ago (meeting of November 20th, 1874, Vol. XIV, No. 

 93, p. 189, of the published proceedings) lexliibited several burettes mounted 

 on stands, and delicately graduated for close, volumetric analj^sis, differing 

 from each other, but each having the screw and spring valve adjustment, 

 and also one of the rod-stoppered kind, having the screw and top spring 

 lever adjustment. 



I now exhibit and shall explain three others also mounted, and delicately 

 graduated, yet still more improved. 



The shortest one (Fig. 1 in the annexed plate), has a capacity of 100 cc, 

 with its scale divided into tenths, or one thousand degrees. The glass rod 

 inside of the tu])e is operated by means of a thumb-screw (A) which works 

 against a horizontal lever (B) under the stand. The lower end of the light 

 vertical iron rod (C) inside of the wooden upright of the stand, rests upon 

 the front of the lever, and its upper end encircles the glass rod directly under 

 its knob. By turning the thumb-screw, the iron rod, and with it the glass 

 one, may be raised or lowered, and the vent of the burette opened or closed 

 at pleasure. The flow may thus be completely controlled or instantly 

 stopped. 



The second instrument (Fig. 2 in the plate) is between four and five feet 

 long, and has a capacity of 240cc, with its scale divided into tenths or two 

 thousand four Imndred degrees. It is operated with the thumb-screw (A) 

 like the shorter instrument from which it dillers in construction only in the 

 position of the screw and lever and shape of the latter. The screw is placed 



