T I C 



It has not yet been reduced to the metallic ftate. It is 

 infufible/icryJ before the blow-pipe, but with borax it melts 

 into a tranfparent glafs. It differs from alumina by its 

 infolubility in hydrate of potafh ; from yttria by its purely 

 aftringent tafte without fweetnefs ; and by the property its 

 folutions poffefs of being precipitated by boiling, when they 

 do not contain too great an excefs of acid. It differs from 

 zirconia by the following properties : I. After being heated 

 to rednefs, it is flill capable of being diffolved in acids. 

 2. Sulphate of potadi does not precipitate it from its folu- 

 tions, while it precipitates zirconia from a folution contain- 

 ing even a confiderable excefs of acid. 3. It is precipitated 

 by oxalate of ammonia, which is not the cafe with zirconia. 

 Sulphate of thorina cryflallizes readily, while fulphate of 

 zirconia, fuppofing it free from alkali, forms when dried a 

 gelatinous tranfparent mafs, without any tendency to 

 cryftallization. 



Thorina combines with the different acids. The fulphate 

 of thorina is foluble, and yields tranfparent cryftals, which 

 are not altered by expofure to the air, and which have a 

 ftyptic tafte. 



The nitrate and muriate of thorina do not cryftallize. 

 The carbonate of thorina is very readily formed, the earth 

 having a very great affinity for this acid. None of the 

 other falts of thorina known appear to be capable of 

 cryftallizing. 



THORN, in Geography, a townfhip of Fairfield, in Ohio, 

 having 497 inhabitants. 



THORNBURY, a townfl-iip of Chefter county, in 

 Pennfylvania, having 200 inhabitants. 



THORNTON, a town of Grafton county, in New 

 Hampfhire, containing 794. inhabitants. 



THRIPS, col. 2, under Variegata, 1. 13, add— The 

 Thrips phyfapus has been fuppofed to do much injury to 

 wheat, rve, &c. by caufing the young flowers to decay, and 

 thus preventing the growth of the embryo grain. Some, 

 however, have difputcd this opinion, contending that the 

 thrips does not attach itfelf to inch of the cereaha as are in 

 a perfeftly healthy ftate, but rather to fuch as are difeafed, 

 by having the germina covered with the duft of a very 

 minute fungus, often growing on wheat, &.C. and belonging 

 to the genus iEcidium or Lycoperdon, and which appears 

 in the form of a flattifh, fmooth, irregular exfudation of a 

 yellow colour in various parts of the plant. (See on this 

 lubicft, vols. iii. iv. and v. of the Tranfaftions of the Lin- 

 naean Society.) The ingenious Mr. Kirby, however, feems 

 convinced, that the thrips is in reality an infeft highly 

 injurious to corn, by deriving its nourifhment from the 

 embryo grain. Shaw's Zool. vol. vi. 



TIC DouLEUREUX, in Medicine, an extremely painful 

 difeafe of the nerves of the face, commonly, if not ex- 

 clufively, afTcdting fome branch of the fifth pair of nerves, 

 and moft frequently the infra-orbital branch, where it 

 pafTes through the foramen, fo named in the cheek. 



The complaint commences with flight and almoft imper- 

 ceptible attacks of pain, and generally without any warning ; 

 though feme patients feel in the affecled part peculiar 

 and inexphcable fenfations preceding its approach, from 

 which they announce with horror the coming enemy ; the 

 patient at the fame time enjoying a good or an indifferent 

 Itate of health. The pain, liowever, foon becomes moft 

 acute, fhooting and darting along the various ramifica- 

 tions of the ahefted nerves. It generally continues from 

 a quarter to half a minute, and never exceeds the fpace of 

 one minute. It returns at intervals more or lefs frequent ; 

 there being fometimes fevefal paroxyfms io a few minutes, 



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and at other times there are intervals of from fifteen to 

 thirty minutes, or longer. There is no determinate period ; 

 we always find the utmoft irregularity even in the fame 

 patient. 



The pains vary in their degree of intenfity, at one time 

 exciting the moft piercing cries, and diflraftcd writhings 

 and motions in the miferable patient ; while at another, 

 they are more bearable. When at the acme of their 

 violence, the parts affe6led are often convulfed, and fome- 

 times various contortions and grimaces are obfervable. 

 Thefe are to be diflinguifhed from the convulfive twitchings 

 of the mufcles, with which the difeafed nerves communicate, 

 and which are occafioned by irritation from the exceflive 

 pain ; while tlfe contortions and grimaces are voluntary, 

 being caufed by the patient's writhing and twifting from the 

 agony of his torture, and may be prevented by a firm 

 refolution to refift any impulfe of fhrinking from the attack. 



The pain does not always confine itfelf to the feat of 

 the difeafe, but darts with the rapidity of lightning to the 

 neighbouring parts, fhooting in different direcfioiis hke 

 radii from a centre. It rarely gives warning of its approach, 

 and often the firft fign of an attack, is the patient's ftarting 

 up in a ftate little fhort of phrenfy. In this condition, 

 fome patients beat the part with violence, or forcibly rub 

 it with fome rough fubftance till excoriation takes place ; 

 and in fome inftances, they have fucceeded in diminiftiing the 

 intenfity of the pain. 



The pains are more frequent during the day than in the 

 night, probably from there being fewer caufes of irritation ; 

 and they are more frequent during converfation than in 

 filence ; and flill more fo, at the time of maftication, when 

 the attacks often fucceed each other with fuch rapidity 

 as to appear like one continued paroxyfm, with fcarcely 

 one interval of ceffation. The eye at times is red, inflamed, 

 and watery, as we fometimes obferve in fevere tooth-ach. 

 In other cafes, it is particularly dry, and in fome patients a 

 copious flow of faliva fucceeds a paroxyfm. In general, 

 only one fide of the face is affefted with this dreadful 

 malady. But as there are cafes recorded in which both 

 fides fuffered at the fame time, we cannot lay it down as a 

 certain characleriftic of the difeafe. Fouquet obferved 

 at Montpellier two women who had both cheeks affefted at 

 the fame time ; and Pujol knew a lady, who, for feveral 

 months, had the pain in one cheek, which after a while was 

 free from pain ; but the other cheek was immediately attacked 

 in the correfponding place, the pain continuing for two 

 months, and then refuming its former pofition. 



When the difeafe continues for a great length of time 

 with increafing violence, the patient can neither obtain 

 refl by night nor by day. His appetite falls ; and, as may 

 be expefted, there is fome degree of feveriftinefs. But this 

 rarely happens, and only in cafes of the utmoft fcverity. 

 The complaint ufually terminates without any apparent 

 caufe, leaving the patient for a time to enjoy the comforts 

 of life. But whoever has had one attack may with con- 

 fiderable certainty anticipate another ; and though he is 

 to-day well, and free from all pain, to-morrow's dawn may 

 uftier in a renewal of his torment. So varied is the 

 duration of this affeftion, and fo limited is our knowledge 

 of it, that we can afTign no determinate or even probable 

 period for its continuance ; and unlefs a cure is effected it 

 returns at intervals more or lefs frequent, and wnth in- 

 creafed violence, till the great final cataftrophe, which, 

 however, it does not feem to accelerate. For though 

 Dr. Banfch is fald to have died of it, we can place little 

 rehance on the report, and fubfequent cafes and obferv- 

 ations do not corroborate fuch a fuppofition. 



Hartenkeil, 



