THE FINGER-TEST. 109 
ined by placing it between the eye and the light. At dif- 
ferent degrees of concentration the following indications 
successively occur:* ‘1. Two drops separate, that on the 
thumb and below is the larger. 2. The drops become 
nearly equal, and do not separate until the fingers are 
drawn more widely apart. 3. By the separation of half 
an inch a thread is drawn out which finally breaks below; 
the end of the thread becomes claviform’ (club shaped), 
‘and it rises slowly toward the finger. 4. The same 
thing occurs at a greater distance; the end of the thread 
is folded back, and gives to the thread the shape of a rib- 
bon or long strip, which rises more rapidly than before. 
5. After a greater separation of the fingers the thread 
breaks, being very fine at the end, which turns aside and 
twists up like a corkscrew. It does not fold itself upon 
the rest of the thread as before, and the thread does not 
increase in volume except by the cohesion which draws the 
particles toward the finger, which is the only adhering 
point. A little more concentration prevents the thread 
from shrinking at all upon itself.’ 
“In the United States the manufacturers of sugar from 
cane juice use the proof by the touch, and consider syrup 
sufficiently concentrated when the broken thread curls up 
in the form of a corkscrew, or the fifth of the degrees 
above described.” 
It is essential, however, to the correctness of these indi- 
cations as well as of those of the thermometer, that the 
syrup be of a standard degree of purity, such as will uni- 
formly result from the juice of ripe cane of good quality 
subjected to the mode of treatment already indicated. The 
presence of impurities such as are found in imperfectly 
defecated syrups, or an excess of either acid or lime, be- 
* See Dictionnaire de l’Industrie, p. 407. Paris, 1841, 
4.» 8G 
