BAIRD &TATLOCK. (LONDON) LTD. 



5009-5010 



5009-5010 (Section) 



5009 s 



Viscometer, Sir Boverton Redwood's. The recognised standard instrument for testing 

 viscosity of oils. This apparatus has been adopted by the Mineral Oil Association as 

 its standard for measuring viscosity. Standardised by Mr. G. A. Berry, assistant to 

 Sir Boverton Redwood. Price, complete with thermometers and certificate of verification, 

 in portable mahogany case 



5010 s Viscometer as above, without case 



5011 s Thermometers for above, with N. P. L. Certificate (tested at every 10 F.) . . per pair 



5012 s Extra thermometers for temperature to 340 F. . . . . . . . . ,, 



5013 Flask with mark on neck, 50 cubic centimetres capacity, for use with above apparatus 



each, 6d. ; per doz. 



Journal of Society of Chemical Industry, vol. v., p. 126. 



DESCRIPTION OF THE APPARATUS. 



The instrument consists of a silvered brass oil-cylinder, furnished with an agate jet, and surrounded by a 

 copper bath. A copper tube, closed at the lower end, projecting at an angle of 45 from the side of the bath, near 

 the bottom, provides a means of heating the bath liquid, and by the use of a revolving agitator, which forms part 

 of the apparatus, the heated liquid rising from the copper tube can be uniformly distributed through the bath. The 

 agitator carries a thermometer to indicate the temperature of the bath. The oil-cylinder is furnished with a 

 stopper, consisting of a small brass sphere attached to a wire, the sphere resting in a hemispherical cavity in 

 the agate jet. A short standard, attached to the oil-cylinder, carries a clip to support a thermometer in the 

 oil. Inside the oil-cylinder, and at a short distance from the top, is fixed a small bracket, terminating in an up- 

 turned point, which forms a gauge of the height of the oil level. The instrument is supported on a tripod stand 

 provided with levelling screws. 



DIRECTIONS FOR USE. 



The bath is filled with a suitable liquid to a height roughly corresponding with the point of the gauge in the 

 oil-cylinder. Water answers well for the temperature up to 200 F., and for higher temperatures a heavy mineral 

 oil may be used. The liquid having been brought to the required temperature, the oil to be tested, previously 

 brought to the same temperature, is poured into the oil-cylinder, until the level of the liquid just reaches the 

 point of the gauge. A narrow necked flask, holding 50 cubic centimetres to a point marked on the neck, is placed 

 beneath the jet in a vessel containing a liquid of the same temperature as the oil. The ball valve is then raised, 

 a stop watch at the same time started, and the number of seconds occupied in the outflow of 50 cubic centimetres 

 noted. It is of the greatest importance that the oil-cylinder should be filled exactly to the point of the gauge, 

 after inserting the thermometer, and that the given temperature should be precisely maintained during the experi- 

 ment, a difference of J degree F. making an appreciable alteration in the viscosity of some oils It is also essential 



5 15 

 5 







1 18 

 12 



056 



(CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS. 



913 



