Abstract: A tissue processor for processing tissue samples for histological analysis. The processor comprises two retorts, wax baths, reagent containers, a pump and valve. The vale distributes the reagent from one container to either retort. Separate reagent lines connect the wax baths to the retorts. A method of infiltrating a sample containing a reagent such as a dehydrating reagent like an alcohol, where the infiltrating material is heated to a temperature at or above the boiling point of the reagent, to boil off the reagent when the tissue sample is contacted by the infiltrating material. The pressure in the retort may be reduced to lower the boiling point of the reagent.