Cramer was born in Quedlinburg where his father was a businessman involved in the iron ore industry.
He became acquainted with Gottfried Jacob Jänisch (1707–1781) who helped Cramer to move to Leiden where he also had a friend in Carl Linnaeus.
Cramer moved to Leiden and met with several scholars in a "society of gentlemen" including Jan Frederik Gronovius, Linnaeus, Herman Boerhaave, Gerard van Swieten (1700–1772), and Isaac Lawson (1704–1747).
Lawson hired Cramer for his laboratory and helped in the writing of Elementa Artis Docimasticae published first in 1741.
[1] Cramer used the idea of "menstrua", an idea of a substance that he defined as ".. which being applied to others according to certain Rules, dissolve them so as to adhere themselves in a State of Division to the Particles of the Body dissolved, and cannot separate from them again of their own accord."