Definition of "milty"

During the summer, he studied calmars at Lisbon, but found no appearance of any roe, nor any reservoir which appeared to be destined for the reception of the seminal liquor; and it was in the middle of December, that he began to discern the first traces of a new vessel replete with a milty juice.

1792, George Louis Le Clerc, Barr's Buffon. Buffon's Natural History, page 126