What did Gideon Harvey (late XVII century) mean by "juice of porcelain"?

Question

In Morbus anglicus by Gideon Harvey (1666), one can find references to "juice of porcelain":

among Herbs, Lettice, Endive, Succory, Sorrel, Porcelain, Chervil, &c. but note that they must be boil'd

He tells us, that the juice of Porcelain being drunk, is a most excellent and powerful remedy.

Similarly, Newton, 2010 says, referencing A general treatise of the diseases of infants and children by John Pechey (1697):

To achieve the analgesic effect, certain ingredients had to be added to the medicines, such as poppies or opium, the oil of roses, lupines, mallows, lettuce, juice of porcelain, and nightshade

Setting aside the fact that I can't find "porcelain" in the copy of Pechey, 1697 I found on the Internet, what kind of plant (I'm assuming it's a plant) could "porcelain" mean?

Answer 1

He was most likely referring to Purslane

Purslane – also called ‘porcelain’ – is known to many only as a garden weed; in fact it is also a native salad plant already appreciated during the Middle Ages. The fleshy leaves have a crunchy texture and a fresh, slightly sour taste. The flower buds can be used as a substitute for capers

Purslane has a long tradition of thousands of years as a food and remedy. It was known as a medicinal plant as early as the eighth century BC. in ancient Babylon. The mucilages it contains are presumably responsible for its soothing effect on heartburn and other stomach ailments. But Portulaca oleracea has also been harvested as a salad and vegetable plant for several thousand years. In the Middle Ages the plant was cultivated and there are also cultivated forms with slightly wider leaves, mostly yellowish. Even the seeds came both as a remnant and as a food. With the seeds of purslane and other wild plants, the Australian aborigines prepared the so-called seedcakes, a kind of bread.

Further to @StuartF's comment regarding the etymology of the word porcelain, eat the weeds, and other things too, says

The words “purslane” and “porcelain” have the same source and similar development. Latin for sow (pig) was porca. It was also the Roman slang for the vulva, and the plant was used for uterine complaints. A diminutive of that, little vulva, became porcillac in Italian to porcellana in old French then to English as purslane. For porcelain, it went from porca to porcella which was the nickname of the cowrie shell because of its vulva-like appearance. In Italian the shell became porcellina. When a glaze was developed for china, it was named after the cowie shell because of its similar shiny appearance and became porcelain then into English as porcelain.