This section is from the book "Mrs. Rorer's Vegetable Cookery And Meat Substitutes", by Sarah Tyson Rorer. Also available from Amazon: Mrs. Rorer's Vegetable Cookery And Meat Substitutes.......
Select perfectly clean mushrooms that will not require washing; remove the stems; string the mushrooms on a long cord, using a darning or trussing needle. Hang in the sun and wind. As soon as the sun goes down, bring in and hang near the kitchen fire where they will have sufficient heat to thoroughly finish the drying. Put these in a cheesecloth bag lined with waxed paper; keep in a perfectly dry place. When wanted for use, soak them in water or milk for two hours and cook them without draining.
Stem, wash and peel the mushrooms. Pack them in glass jars with glass tops; adjust the rubbers, put the lids on loosely, and stand the jars in a wash-boiler, the bottom of which has been protected with a rack. Surround them half way up with cold water. Cover the boiler; bring to boiling-point and boil continuously for one and a half hours. Lift three jars from the boiler; take the lids off and drop them in a kettle of boiling water. Fill two jars from a third. Lift the lids with a skimmer, touching them only on the edge; put them back on the jars and fasten. Stand the jars back in the boiler. When you have filled the last jar, cover the boiler, bring the water again to boiling-point and boil rapidly for twenty minutes. Lift the jars when they are cool, examining them to see that the tops are firmly fastened.