T U R 



T U R 



courfe of two or three years, being therefore rather of a 

 biennial nature. 



TURNESOLE, or Turnsole, in Botany. See He- 

 tlOTROPiL'M, and Croton Tin8orium. 



Some have tranflated turnefole by the Englifh ■wordfun- 

 fioiuer, wliich has led many to fuppofe that the great yel- 

 low fun-flower, which we keep in gardens, was the plant 

 that afforded the turnefole colour : but this is a miftake ; 

 and it is to be obferved, that the true turnefole plant, or 

 heliotroplum trtcoccum, is very common in the fields of 

 France, efpecially about Montpelier, and in Germany, but 

 docs not grow wild with us in England. 



The juice of the berries of the turnefole, rubbed upon 

 paper or cloth, at the firft appears of a fredi lovely green, 

 but prefently changes into a kind of blueilh purple. It is 

 faid that the common blue paper receives its colour from 

 this juice. The fame cloth, afterwards wet in water, and 

 wr jng out, will turn the water into a claret colour ; and it 

 is to be obferved, that the rags of cloth tinftured by this 

 juice, and turned red by acids, are ufually called turnefole 

 in the druggifts' fhops, and employed for colouring wines 

 and other liquors. M. Niffole, of the French Academy of 

 Sciences, fays, that the colouring juice is obtained, not 

 from the berries, but from the tops of the plant, gathered 

 in Augufl, ground in mills, and then coipmitted to the 

 prefs. The juice is expofed to the fun about an hour ; the 

 rags dipt in it, dried in the fun moiftened by the vapour 

 which arifes during the flaking of quicklime with urine, 

 then dried again in the fun, and dipt again in the juice. 

 The Dutch and others are faid to prepare thefe rags and 

 turnefole in the mafs from other ingredients, of which archil 

 is a principal one. Boyle's Works abr. vol. ii. p. 19. 

 Neumann's Chem. by Lewis, p. 433. 



The Dutch procefs for making the blue called turnefole 

 is as follows : Lichen, archil, or in cafe this lad cannot be 

 obtained, the greater mofs of the oak, is dried, cleaned, and 

 pulverized in a mill, refembling the oil-mill, and then fifted 

 through a bi-afs wire fieve, the interftices of which do not 

 exceed one millimetre in widtli (-r^Tth of an inch). The 

 fifted powder is then thrown into a trough, and mixed with 

 an alkali called vedas, which is nothing elfe but the cendres 

 gravelees in powder. The proportion is one part by weight 

 of the alkali, to two parts of the pulverized vegetable. 

 This mixture is moiftened with a fmall quantity of human 

 urine ; the urine of other animals does not contain a fuffi- 

 cient quantity of ammoniac. The mixture ferments, and is 

 kept moift by fuccelfive additions of urine. As foon as 

 the materials have become red, they are transferred into 

 another trough, where they are again moiftened with urine, 

 and ftirred to renew the fermentation. Some days after- 

 wards, the pafte acquires a blue colour, in which ftate 

 it is carefully mixed with one-third of excellent potafh 

 v?ell powdered ; and vjith this new mixture certain trays 

 are filled, which are one metre (397 inches) deep, and eight 

 decimetres (31]- inches) wide. When the fermentation 

 which takes place for the third time has given the pafte a 

 confiderably deep blue colour, chalk or powdered marble 

 is added, and the whole is well and perfeAly mixed. This 

 laft addition is made, not to improve the quality of the blue, 

 but to add weight. It is merely an affair of profit. The 

 blue thus prepared is put into iron moulds 32 centimetres 

 long and 22 fquare at the end (14 inch by ^^,ths of an inch). 

 The moulded pieces are then placed upon deal planks, m 

 well-aired lofts, to dry ; after which they are packed in 

 cail<s for falc. 



The Hollanders made a fecret of this procefs : and in 

 order to miflcad, they have publifhed, that the blue was 



made with rags coloured by the plant turnefole ; whence it 

 has obtained its appellation. The Enghfh writers have 

 ufed this denomination : but the dry-falters, or dealers in 

 drugs, diftinguifh thefe paftils by the name of Htmus. We 

 may derive much profit by carrying this difcovery into 

 praftice. 



The principal ufc of this plant is in dyeing : in order to 

 which, the juice is infpiffated and prepared with calx and 

 urine, into blue cakes ; which are ufed alfo with ftareh, 

 inftead of fmalt. 



The lixivium of this plant in lime-water and urine, or in 

 the volatile fpirit of wine, turns marble blue. See Colour- 

 ing 0/" Marble. 



TURNESS, in Geography, a cape on the eaft coafl of the 

 idand of Hoy. N. lat. 58° 41'. W. long. 3° 10'. 



TURNETUM, in our old Law Books, a duty paid to 

 the flieriff for holding his turn, or county-court. 



TURNHOUT, in Geography, a town of France, in the 

 department of the Two Nethes, built in the year I2I2, by 

 Henry IV. duke of Brabant. In the year 1545, the 

 emperor Charles V. gave it to his fifter Mary, queen of 

 Hungary, to enjoy during her life. In the year 1648, after 

 the peace of Munfter, Phihp IV. gave it to princefs Amelia, 

 widow of Frederick Henry of Naffau, from whom it came 

 to the houfe of Orange. The quarter of Turnhout com- 

 prehends fifteen villages ; 25 miles S.S.W. of Bois-le- 

 Duc. 



TURNING, in the Mechanical Arts, is the operation 

 of (haping wood, metal, or other hard fubftanccs, into a 

 round or oval figure, by the aid of a machine called a lathe; 

 which fee. 



In turning, the work or fubftancc to be operated upon is 

 placed in the lathe, and made to revolve with a circular mo- 

 tion about a fixed right line as an axis of motion ; and the 

 exterior furface is worked to its intended figure by means of 

 fome kind of edged tool, which is prefented to it and held 

 faft down upon a fixed reft. The protuberant parts of the 

 work, by its rotatory motion, are carried againft the cutting 

 edge, and cut off, fo as to reduce every part of the outfide 

 furface, to an equal diftance from the axis of motion,*and of 

 courfe it will be of a circular figure. 



The articles which admit of being turned to give then\ 

 their figure, are all fuch as combine the three following pro- 

 perties : I . That they may be fuppofed to have an ima- 

 ginary right line or axis palling centrically through the whole 

 length of the piece : 2. That all the feitions which can be 

 made by planes perpendicular to fuch axis Ihall be circular : 

 and 3. That the centre of all fuch circles fhall coincide with 

 the axis or centre line. 



It (hould be obferved, that a piece of work may have 

 two or more centre fines in different parts or in different 

 direftions ; but it muft in that cafe be formed or turned 

 at two or more fuccelfive operations, becaufe what can be 

 done at once fixing in the lathe, muft come within the above 

 definition. 



The work may be turned hollow, fo as to make a cavity 

 withinfide ; or work may be turned on the outfide, to give 

 form to the external furface ; and frequently work is turned 

 both without and within ; but in either cafe, the above defi- 

 nitions will apply. 



Diodorus Siculus fays, the inventor of the art of turning 

 was a nephew of Daedalus, named Talus ; and that the re- 

 putation which he acquired by this invention excited the 

 jealoufy of Daedalus, and induced him to put Talus fecretly 

 to death. Phny afcribes it to Theodore of Samos, and 

 mentions one Thericles, who rendered himfelf very famous 

 by his dexterity in managing the lathe. With this inftru- 



ment. 



