7-Methyl guanine is obtained from 7-methyl-6-oxy-2-chlorpurin (see above) by the action of aqueous ammonia at 150° C. It also results instead of the expected 7-methyl-2-oxy-6-aminopurin, when 7-methyl-6-amino-2-chlorpurin is treated with dilute alkalis (E. Fischer, Ber., 1898, 31, p. 542), owing to ring splitting in the 1~6-position, followed by eliminating of halogen acid. Thiopurins.-W. Traube (Ann., 1904, 331, pp. 66 seq.) has obtained many compounds of the purin group by using thiourea, which is condensed with cyan acetic ester, &c., to form thiopyrimidines. These in turn yield thiopurins, which on oxidation with dilute nitric acid are converted into purin compounds, thus:-
H2N CO2R HN·CO HN·CO HN·CO
SC+CH2 → SC+CH2 SC C·NH
| | | | > CH
H2N CN HN-C:NH HN-C-NH2 HN·C·N
Various thiopurins have been obtained by E. Fischer (Ber., 1898, 31, p. 431), principally by acting with potassium sulphydrate on chlorinated purin compounds.
2·6·8-Trithiopurin is obtained from the corresponding trichlorpurin and potassium sulphydrate. It forms a light yellow mass which carbonizes on heating. It is almost insoluble in water and alcohol; but readily dissolves in dilute solutions of the caustic alkalis and of ammonia.
Much work has been done by J. Tafel (Ber., 1900, seq.) on the electrolytic reduction of the members of the purin group. The substance to be reduced is dissolved in a 50–75% solution of sulphuric acid and placed in a porous cell containing a lead cathode, the whole being then placed in a 20–60% solution of sulphuric acid in the anode cell. It is found that xanthine and its homologies take up four atoms of hydrogen per molecule and give rise to the so-called desoxy-compounds, which are stronger bases than the original substances. Uric acid takes up six hydrogen atoms per molecule and gives purone, C5H8N4O2, and it is apparently the oxygen atom attached to the carbon atom number 6 which is replaced by hydrogen, since when purone is heated with baryta, two molecules of carbon dioxide are liberated for one of purone. Consequently purone must contain two urea residues, which necessitates the presence of the >CO groups in positions 2 and 8. (F. G. P.*)
PURITANISM (Lat. puritas, purity), the name given—originally perhaps in a hostile sense on the analogy of Catharism (see Cathars)—to the movement for greater strictness of life and simplicity in worship which grew up in the Church of England in the 16th century among those who thought that there had not been a sufficient divergence from the Roman Church, and which ultimately led to the rise of a number of separatist denominations. Thomas Fuller (Church History) traces the earliest use of the term “Puritan” to 1564. The terms “Precisian,” “Puritan,” “Presbyterian,” were all used by Archbishop Parker in his letters about this time as nicknames for the same party, and ten years later the name was in common use.
See England, Church of; Congregationalism; Presbyterianism, &c.; also D. Neal, History of the Puritans (ed. Toulmin, 5 vols., 1822); E. Dowden, Puritan and Anglican (1901); J. Heron, A Short History of Puritanism (1908).
PURLIEU, a word used of the outlying parts of a place or district, sometimes in a derogatory sense. It was a term of the old English forest law (q.v.), and meant, as defined by Manwood (Treatise of the Forest Laws), “a certain territory of ground adjoining unto the forest,. . .which. . .was once forest-land and afterwards disafforested by the perambulations made for the severing of the new forests from the old.” The owner of free-lands in the purlieu to the yearly value of forty shillings was known as a “purlieu-man” or “purley-man.” There seems no doubt that “purlieu” or “purley” represents the Anglo-French puralé, puralee (O. Fr. pouraler, puraler, to go through, Lat. perambulate), a legal term meaning properly a perambulation to determine the boundaries of a manor, parish, &c.
PURLIN, a term in architecture for the longitudinal timbers of a roof, which are carried by the principal rafters and the end walls and support the common rafters.
PURNEA or Purniah, a town and district of British India, in the Bhagalpur division of Bengal. The town is on the left bank of the little river Saura, with a railway station. Pop. (1901), 14, oo7. It has a bad reputation for fever.
The District of Purnea has an area of 4994 sq. m. and a population (1901) of r,874,794, showing a decrease of 3.6% in the decade. The district extends from the Ganges northwards to the frontier of Nepal. It is a level, depressed tract of country, consisting for the most part of a rich, loamy soil of alluvial formation. It is traversed by several rivers flowing from the Himalayas, which afford great advantages of irrigation and water-carriage; in the west the soil is thickly covered with sand deposited by changes in the course of the Kusi. Among other rivers are the Mahananda and the Panar. Under Mahommedan rule Purnea was an outlying province, yielding little revenue and often in a state of anarchy. Its local governor raised a rebellion against Suraj-ud-daula in 1757, after the capture of Calcutta. The principal crops are rice, pulses and oilseeds. The cultivation of indigo is declining, but that of jute is extending. The district is traversed by branches of the Eastern Bengal railway, which join the Bengal and North-Western railway at Katihar.
PURPLE, a colour-name, now given to a shade varying between crimson and violet. Formerly it was used, as the origin of the name shows, of the deep crimson colour called in Latin purpura, purpurea and in Greek πορφύρα, πορφύρεος (from πορφύρειν, to grow dark, especially used of the sea). This was properly the name of the shellfish (Purpura, Murex) which yielded the famous Tyrian dye, the particular mark of the dress of emperors, kings, chief magistrates and other dignitaries, whence “ the purple” still signifies the rank of emperors or kings.
The title of porphyrogenitus (Gr. πορφυρογέννητος) was borne particularly by Constantine VII., Byzantine emperor, but was also used generally of those born of the Byzantine imperial family. This title, generally translated “born in the purple,” either refers to the purple robes in which the imperial children were wrapped at birth, or to a chamber or part of the imperial palace, called the Porphyra. (πιόρφυρα), where the births took place. Whether this Porphyra signified a chamber with purple hangings or lined with porphyry is not known (see Selden, Titles of Honour, ed. 1672, p. 60 seq.).
PURPURA, in pathology, a general term for the symptom of purple-colored spots upon the surface of the body, due to extravasations of blood in the skin, accompanied occasionally with hemorrhages from mucous membranes. The varieties of purpura may be conveniently divided as follows: (a) toxic, following the administration of certain drugs, notably copaiba, quinine, ergot, belladonna and the iodides; also following snakebite; (b) cachectic, seen in persons suffering from such diseases as tuberculosis, heart disease, cancer, Bright's disease, jaundice, as well as from certain of the infectious fevers, extravasations of the kind above mentioned being not infrequently present; (c) neurotic; (d) arthritic, which includes the form known as “ Purpura simplex,” in which there may or may not be articular pain, and the complaint is usually ushered in by lassitude and feverishness, followed by the appearance on the surface of the body of the characteristic spots in the form of small red points scattered over the skin of the limbs and trunk. The spots are not raised above the surface, and they do not disappear on pressure. Their colour soon becomes deep purple or nearly black; but after a few days they undergo the changes which are observed in the case of an ordinary bruise, passing to a green and yellow hue and finally disappearing. When of minute size they are termed “ petechiae ” or “ stigmata,” when somewhat larger “ vibices," and when in patches of considerable size “ ecchymoses.” They may come out in fresh crops over a lengthened period.
Purpura rheumatic (Schönlein's disease) is a remarkable variety characterized by sore throat, fever and articular pains accompanied by purpuric spots and associated with urticaria and occasionally with definite nodular infiltrations. This is by many writers considered to be a separate disease, but it is usually regarded as of rheumatic origin.
Purpura haemorrhagica (acute hemorrhagic purpura) is a more serious form, in which, in addition to the phenomena already mentioned as affecting the skin, there is a tendency to the occurrence of hemorrhage from mucous surfaces, especially from the nose, but also from the mouth, lungs, stomach, bowels, kidneys, &c., sometimes in large and dangerous amount. Great physical prostration is apt to attend this form of the disease, and a fatal result sometimes follows the successive hemorrhages, or is suddenly precipitated by the occurrence of an extravasation of blood into the brain.