For historical interest, Guilly’s delightful description of the processing of the casing is reproduced verbatim. Today in Western countries one would simply get the sausage casing from a friendly butcher.
Buy one pig’s casing (tripe) as the remainder can be kept for other occasions. Take the casing by the end, put on a piece of board and with the border of a bowl carefully scrape down dirt till it comes out by the other end. If it is too long, cut it into three. Rinse the water, putting the end into the tap and let the water run through. When all the dirt is out, take a chopstick, take the casing by the edge, fold about 1-2 inches of the board right in and with a stick push this end right through until you come to the other end. Get a good hold of the first end and turn the skin inside out. You will succeed with a little practice. When the casing is turned inside out, again take a bowl or cup, and do the soaping, being careful not to be too rough, as the skin might break. Go through this process 2-3 times until it is quite clean and the skin is evenly thin. Remove all the water from it, put a teaspoonful of salt in it and squeeze all the remainder of the water, then rinse thoroughly. This is ready for the filling. Use a tin tube with the upper part of the shape of more or less a bowl, put the tube into the casing and fill the meat in. When all these are done tie the ends, then divide into sections 5 inches long and tie. Between every four sausages have the string fold in 2 tied, so as to be able to hang up. When this is done, dip the bunch of sausages in hot water for half a minute to take off all the salty taste on the outside. Hang them out on a bamboo, keeping them apart, so as to get the full sun. Prick each one 5-6 times with a pin to take out the air, and sun up. See that the day is good for making sausages, as sausages must have a good sunning the first day. This will be ready after 2 days of sunning. What is left over of the casing wash off all the sutate that may be left there, squeeze dry, put in a small bowl, add half a hand of salt and squeeze for the salt to get well in. Then dry in the sun without taking out the salt. When next using take the amount of casing you need, soak in tepid water, squeeze off the salt and if not soft enough put more tepid water and soak. It takes 5-10 minutes. If the weather is bad or doubtful after cutting the meat do not put in the casing. Keep the meat mixed with the ingredients in a cool place, stirring with a wooden spoon two times a day. This can be kept for two or three days. Be careful not to put in casing when there is not enough sun, as the sausages will turn sour, if the weather is warm, besides worms might appear.