There was no mystery as to its genesis in either region, as it had been shown to be the result of inspissation of.    From Wordnik.com.  [Scientific American Supplement, No. 401, September 8, 1883] Reference

When cold, it should have a density of about 1.38, and mark the 38th degree of Baume's hydrometer; beyond which point of inspissation it would be dangerous to go.    From Wordnik.com.  [The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c.] Reference