Without tasting it, one can tell if lemonade needs more sugar.

Dr Abe V Rotor
Living with Nature - School on Blog [avrotor.blogspot.com]
Paaralang Bayan sa Himpapawid (People's School-on-Air) with Ms Melly C Tenorio
738 DZRB AM Band, 8 to 9 evening class, Monday to Friday [www.pbs.gov.ph]

Seeds of calamansi (Citrus microcarpa) rises to the top as buoyancy (specific gravity) is increased. Thus the more we put sugar, the more the seeds float. If they settle at the bottom, the lemonade needs more sugar. Buoyancy is also explained by the fact that it is easier to swim in seawater than in the swimming pool.
Scientifically the addition of sugar increases the specific gravity of the lemonade. By specific gravity of a liquid we mean the ratio of its density to that of water which is normally 1. This is determined by the use of hydrometer, the same instrument used in determining the concentration of alcohol, acids, oils and other liquids.
The idea of buoyancy that led to our present knowledge of specific gravity came from the first true experimentalist, Archimedes during the golden age of Greek civilization. A story about his discovery was a hilarious one. All of a sudden he emerged from the bathtub and went through the streets shouting, “Eureka! Eureka!”~