Castor oil appears as an ingredient in many older enema recipes and even a few current ones, but people who have tried it will know it is a disappointment. This might seem surprising, as castor oil taken orally can be a startlingly effective laxative. But in fact it only works as a laxative after it has been broken down by pancreatic enzymes in the small intestine. This liberates ricinoleic acid, which is highly irritating to the gut. But in the colon the enzymes are not present, so oil introduced that way remains undigested and inactive, working only as a lubricant.In some older medical literature the digestion of castor oil (and other oils) is described in terms of saponification, e.g. http://chestofbooks.com/health/materia-medica-drugs/Pharmacology-Therapeutics-Prescription-Writing/index.html from 1918: ‘[Castor] oil is saponified in the small intestine to form glycerin and sodium ricinoleate, a soap which is much more irritant than Castile soap to the intestinal mucous membrane.’ This conception seems to be abandoned today. However, it suggested to me the possibility of making a soap from castor oil (i.e. sodium ricinoleate), and trying it in an enema. Some googling revealed reports on this soap by at least two soapmakers who have made it while studying single-oil soaps. (Most soaps are made from mixtures of oils, which sometimes include a low percentage of castor.)I made a batch of castor oil soap over Easter, and it was ready to use after a couple of days. 500 grams of castor oil produced a bit over 700 grams of soap, of which close to 25% was water. The weight declined steadily due to evaporation, reaching ~640 g by last Saturday. I decided to use one-eighth of the batch in an enema, reasoning that it would represent approximately a 65 ml dose of castor oil. I cut 80 grams of soap into ~5 g chunks which dissolved quite readily in hot water, then made up the water to 2.5 litres, my usual volume. I injected it slowly at 42–43°C with a double balloon nozzle and a Higginson syringe, one bulbful or ~80 ml every 30–40 seconds, waiting for any cramps or urges to clear before proceeding. Cramping began within five minutes, it took 11 minutes to inject 800 ml, at the end of 20 minutes I had only taken 1200 ml and the cramps were unremitting. I decided this was enough for a first try and expelled. Expulsion was quick and thorough, finished in less than 10 minutes, with no ‘repeats’, but I was left with a bellyache that faded over an hour or so.I have two soaps that I regularly use for enemas: a liquid Castile soap and a tallow and coconut oil soap sold in flake form as a laundry soap. The latter is a little stronger, and I generally take 125 g in 2.5 litres of water. I gather this is a stronger solution than most people use, but the castor oil soap solution worked much more strongly still. I concluded I should probably use a weaker solution, or at least inject it quicker to get it in before the cramping begins in earnest.Nine hours later I thought I would use up the rest of the solution. Unlike more familiar solid soaps, the solution had not set on cooling to room temperature. I reheated it to the low 40s C and injected it this time as rapidly as possible, held for five minutes and expelled. Results were similar to the first time, only the bellyache lasted longer, a couple of hours.Will I do this again? Well, I’ve got at least seven more doses of the soap left (more if I use a weaker solution). I certainly wouldn’t want to use it for every enema, but I can see myself taking it again when I feel like something a bit out of the ordinary.