Hot Springs 3 - Carbon Dioxide Hot Springs 二酸化炭素泉

Ingredients: at least 1g of free carbonic acid per 1kg of water
Characteristics: when bathing, carbonic acid bubbles stick to the skin
Indications: this type of hot springs share the same indications as Simple Hot Springs, and also treat high blood pressure, atherosclerosis, cuts and burns. Drinking the water is good for chronic digestive disorders and chronic constipation.
Discussion: To my knowledge, carbon dioxide or carbonic acid have not been listed in Chinese materia medica, though it wouldn't surprise me if they actually have, the Chinese can be quite thorough about categorization. Looking at the few indications listed, this type of spring seems to have a descending effect, as may be deduced from the fact that it lowers blood pressure and treats constipation. It also may actually be cooling, since it treats burns, and as many HBP and chronic digestive disorders involve some heat. Descending and cooling are yin actions, and it is possible carbon dioxide hot springs are also softening, another yin action, as they treat hardened arteries.

A lot of speculation here, and one possible contradiction. As I discussed earlier, the actions of simple hot springs seem to be entirely yang. However, carbon dioxide hot springs appear to have yin actions, but then they also treat all the indications of simple hot springs, which call for yang actions.

Is it a contradiction to have both yin and yang actions? No, many TCM formulas are both cooling and warming, or draining and supplementing. Since this type of spring can be considered a kind of formula, with carbon dioxide mixed with simple hot spring water, it could have complex actions and varied indications. Finally, hot springs are generally mild and just one or two baths probably won't affect a person all that much. But if one was considering a week-long trip to a hot springs resort, taking into consideration the ingredients of the water might be wise.