188 Prof. Hare's Litramcter. 



is long enough to admit of about 70 degrees. Close to this 

 scale, a vernier v is made to slide, so that the divisions of the 

 scale are susceptible of subdivision into tenths, and the whole 

 height of the tubes into about 1100 parts, or degrees. 



On the left of the tube, there is another strip of brass, with 

 another set of numbers so situated as to divide each of the 

 degrees in the scale above mentioned into two : so that, agree- 

 ably to this enumeration, the height of the tubes is, with the 

 aid of a corresponding vernier, divided into 2200 parts or de- 

 grees. 



A small strip of sheet-tin k is let into a notch in the wood, 

 supporting the tubes, in order to indicate the commencement 

 of the scale. At distances from this of 1000 parts, and 2000 

 parts (commensurate with those of the scale), there are two 

 other indices TT to the right-hand tube. Let a small vessel 

 containing water be made to receive the lower end of the tube 

 by the side of which the scale is situated, and a similar vessel 

 of any other fluid, whose gravity is sought, be made to receive 

 the lower end of the other tube ; so that the end of the one 

 tube may be covered by the liquid in question, and the end 

 of the other tube by the water. 



The piston of the syringe being previously pushed into the 

 chamber as far as possible, is now to be moved in the opposite 

 direction. By these means the air is rarefied in the chamber 

 and in the glass tubes, and consequently it allows the liquids 

 to rise into the tubes, in obedience to the greater pressure of 

 the atmosphere without. If the liquid to be assayed be heavier 

 than water ; as, for instance, let it be concentrated sulphuric 

 acid, it should be raised a little above the first index, at the 

 distance of 1000 degrees from the common level of the orifices 

 of the tubes. The vessels holding the liquids being then 

 lowered, so that the result may be uninfluenced by any in- 

 equality in the height of the liquids in them, the column of 

 acid must be lowered until its upper surface coincide exactly 

 with the index of one thousand. Opposite the upper surface 

 of the column of water, the two first numbers of the specific 

 gravity of the acid will then be found ; and by duly adjusting 

 and inspecting the vernier, the third figure will be ascertained. 

 The liquids should be at the temperature of 60°. 



If the liquid under examination be lighter than water, as in 

 the case of nearly pure alcohol, it must be raised to the upper 

 index. The column of water measured by the scale of 1000, 

 will then be found at 800 nearly ; which shows that one thou- 

 sand measures of alcohol are, in weight, equivalent to 800 

 measures of water — or, in other words, 800 is ascertained to 

 be the specific gravity of the alcohol. 



The 



