(From the Arabic sorah). The chronic nettle rash. It is called essere, sora, and sara, by the Arabians; by Sydenham, a bastard or scorbutic erysipelas, with or without ulcerations; the nettle spring, from its resemblance to the eruptions excited by the stinging of nettles. This appears to be a disease which Pliny calls zoster, and some others zona. Dr. Cullen observes, that the nettle rash of the English is considered as the urticaria; but the disease described by Dr. Heberden in the London Medical Transactions, which Cullen hath often seen, is totally different from the urticaria of nosologists, as it is chronical without fever, and may be associated with the impetigines. The chief distinction consists in the hardness felt in the skin.

The essera is a species of tumour not mentioned by the Greeks nor Latins. It is truly a chronical disorder, and is seated in the cutis. Some persons are affected with it only when the weather is frosty, others chiefly in the hottest months. Persons of all ages and of both sexes are subject to it. Sennertus attributes the disease to the serum; Dr. Heberden to an acrimony not unlike the fish poison, as the diseases are nearly the same.

This disorder appears in the skin in the form of small white hard tubercles, generally with a dark irritable point; sometimes these are broad and long, such as appear after being lashed with a whip; an intolerable-itching attends; and generally the skin is inflamed in the spaces between the eruptions. The elevations appear suddenly: they seldom continue long; but dis-appear and appear again in another part. When many of the tubercles appear together, the part seems swelled. In some instances this disorder totally disappears in a few days, in others it hath continued some months, and even years, disappearing at times, but returning after very short intervals. For the most part the itching is the only inconvenience; and this indeed is sometimes so great as to deprive the patient of sleep; but sickness, headach, or other troublesome symptoms sometimes come on during the presence of the eruptions; at others on their suddenly sinking in. We have found headach, etc. supervene on bathing them with cold water, when they were very numerous and highly inflamed. They have been attributed to the bites of insects; and we think we have found, that those who wear boots are less subject to them in the legs.

Serapion says, there are two species of essera; but his distinctions do not seem well grounded.

The essera should be distinguished from that species of itch which appears in the form of dry pimples at the first; but these soon after have a thin serum lodged on their apex, like a small vesicle. Some authors confound the essera with the epinyctides; but the latter have also a thin humour which oozes from them. No danger attends this complaint.

The only indication is to allay the itching; but this object is with difficulty attained. Rubbing them with parsley juice has been said to take off this chief inconvenience; but the saliva is still more effectually employed in the same way. When it has been of some continuance, diuretics have been of service; interposing purgatives of the saline kind, to succeed a dose of calomel given at bedtime. See Sennertus, Sydenham, and Dr. W. Heberden's Remarks on the Nettle Rash, in the second volume of the London Medical Transactions.