lactodensimeter

from The Century Dictionary.

• noun A kind of lactometer furnished with scales intended to show what proportion of the cream, if any, has been removed from a sample of milk by skimming.

from the GNU version of the Collaborative International Dictionary of English.

• noun A form of hydrometer, specially graduated, for finding the density of milk, and thus discovering whether it has been mixed with water or some of the cream has been removed.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A form of hydrometer for finding the density of milk, and thus discovering whether it has been mixed with water or had some of the cream removed.