Première page
Page précédente
Page suivante
Dernière page
Réduire l’image
100%
Agrandir l’image
Revenir à la taille normale de l’image
Adapte la taille de l’image à la fenêtre
Rotation antihoraire 90°
Rotation antihoraire 90°
Imprimer la page
- TABLE DES MATIÈRES
- RECHERCHE DANS LE DOCUMENT
- TEXTE OCÉRISÉ
- PAGE DE TITRE (Première image)
- Lecture I, Tuesday, February 7th, 1871 : Red colouring substances, madder (p.3)
- Lecture II, Tuesday, February 14th, 1871 : Red colouring substances (continued) (p.7)
- Lecture III, Tuesday, February 21st, 1871 : Blue colouring substances (p.12)
- Lecture IV, Tuesday, February 28th, 1871 : Quercitron, Fustic, Persian Berries, Weld, Aloes, Turmeric, Annatto, Ilixanthine, Lo-Kao, Tannin matters, Gall nuts, Sumach, Divi-Divi, Myrobalans, Catechu (p.18)
- Dernière image
7
The details so essential to success in dyeing this colour are kept by each dyer a secret, but I will attempt, as briefly as possible, to give the main features of the pro-cess. After the bleaching of the fabric is completed, they are passed through Gallipoli oil, and then exposed to the atmosphère in heated chambers. This operation is repeated several times. The next one consists in passing the cloth through a weak alkaline solution. After this they go through a solution of acetate of alumina, and then through a bath of a tannin substance. By these processes, no doubt, the fatty acids of the oil combine with the alumina, as does the tannic acid of the tannin matter, helping to fix the mordant in the fibre of the fabric. On being dyed, the goods assume a rich, dark
red tone, to which brilliancy is imparted by passing the dye fabric through heated soap solutions.
I should occupy too much of your time were I to attempt to enter into the details of the methods by â– which chemists détermine the relative tinctorial powers of roots, madders, and garancines, but I may give you a very simple method of detecting ordinary adultérations of garancine by dye woods and tannin matters. Pièces of blotting paper are dipped into a weak solution of chloride of tin and sulphate of protoxide of iron, and on each of these sheets is sprinkled a little of the suspected garancine. If a dye wood be présent, the chloride of tin paper will assume a red colour, and if tannin matter be présent, the iron paper will be blackened.
LECTURE II.—Delivered TUESDAY, FEBRUARY 14TH, 1871.
RED COLOURING SUBSTANCES (continued}.— MUNJEET; CAMPECHY, PEACH, SAPAN, CANE, AND BAR WOODS ; ALKANET ROOT ; SAFFLOWER ; COCHINEAL, LAC DYE ; MUREXIDE.
Munjeet.—It is to the researches of Dr. John Stenhouse, one of the most eminent and leamed of English chemists, that we are indebted for our knowledge of the true composition of many of the dye-stuffs, and it is to him that we are indebted for the whole of the information we possess in the colouring matters of munjeet, or Rubia munjista.
This peculiar variety of the genus rubia is cultivated exclusively in Asia, and especially in India, where it has been used as a dye-stuff for a long period of time, either alone or mixed with other dyes, to produce a variety of redshades. It is imported into this country from time to time, but has never been extensively used, as the colours produced from it are neither so fast nor so bright as those obtained with Rubia tinctorum.
Whilst the colouring principles of madder are purpurine and alizarine, those of munjeet are purpurine and a yellow colouring matter, named by Dr. Stenhouse munjistine. He has assigned to this latter body the formula C. H. O6. When crystallized from an alcoholic solution, it forma large, beautiful, golden-coloured flakes, which sublimed, give prismatic crystals of an orange-red colour. It is only slightly soluble in cold water, but freely soluble in hot water. Its beat solvent is bisulphuret of carbon, which was em-ployed with success by Dr. Stenhouse in separating the purpurine and munjistine from the other substances existing in munjeet. He States that the munjeet root contains as much colouring matter as the Rubia tinctorum, and, according to Mr. Higgins, of Manchester, it yields from 52 to 55 per cent, of a garancine ; but as it has only half the dyeing power of ordinary garancine, it cannot be employed with advantage for this purpose. The inferiority of munjeet arises from its containing only the comparatively feeble colouring matters, purpurine and munjistine. Munjeet is not much used by calico printers, as the munjistine gives a brownish-purple with salts of iron, which prevents it being employed with that mordant. It is used for spécial shades of Turkey red, the munjistine giving, with salts of alumina, an orange-yellow colour, which is in some instances employed by the dyers.
I have now the pleasure of calling your attention to an important class of dyeing substances, " the dye-woods.”
Campechy or Logwood.—1This wood, obtained from a large tree of the leguminous family, called by the botanist Hematoxylum campechianum, grows abundantly in the West Indies, Mexico, and other states of South America. The best quality is imported from the Bay of Campechy, in the Gulf of Mexico. Large quantifies are also obtained from Jamaica and St. Domingo. The qualifies obtained from Honduras, Martinique, and Guadaloupe are inferior.
Campechy was introduced into Europe by the Spaniards, but it was not till the reign of Elizabeth that it came into use in England, and then only for a short period, after which its employment was forbidden under the severest penalties for upwards of a century.
The discovery of its colouring principle, hematine, was made in 1810, by my learned and venerable master, M. Chevreul (who, although now 85 years old, is still actively engaged in scientific pur suits). Shortly afterwards it was studied by Ermann, who gave it the name of hematoxyline. It was obtained by these eminent chemists as yellowish white prismatic crystals, which become dis-coloured by contact with the oxygen of the air and the small amount of ammonia which the atmosphère contains. It is only slightly soluble in cold water, but much more so in hot. It is very soluble in alcohol, ether, and bisulphuret of carbon. It combines with three équivalents of water, forming a crystalline hydrate, which at 212° F. retains one équivalent.
Hematine in the presence of oxygen, especially under the influence of alkalies, assumes a beautiful purple colour. This colouring matter can be obtained under the form of purple-black crystals, having a metallic lustre, and has received the name of hcmatëine. Hematine has the formula C, 6 H, 4 08, which, on conversion into hema-tëine, becomes C1H,20.,II,0. The hydrate is C, 6 Hi 06,3 H2O, which at 212” F. becomes C1H1406, H.O.
The oxydation, and conséquent colouration, of hema-
Le texte affiché peut comporter un certain nombre d'erreurs. En effet, le mode texte de ce document a été généré de façon automatique par un programme de reconnaissance optique de caractères (OCR). Le taux de reconnaissance estimé pour cette page est de 97,97 %.
La langue de reconnaissance de l'OCR est le Français.
The details so essential to success in dyeing this colour are kept by each dyer a secret, but I will attempt, as briefly as possible, to give the main features of the pro-cess. After the bleaching of the fabric is completed, they are passed through Gallipoli oil, and then exposed to the atmosphère in heated chambers. This operation is repeated several times. The next one consists in passing the cloth through a weak alkaline solution. After this they go through a solution of acetate of alumina, and then through a bath of a tannin substance. By these processes, no doubt, the fatty acids of the oil combine with the alumina, as does the tannic acid of the tannin matter, helping to fix the mordant in the fibre of the fabric. On being dyed, the goods assume a rich, dark
red tone, to which brilliancy is imparted by passing the dye fabric through heated soap solutions.
I should occupy too much of your time were I to attempt to enter into the details of the methods by â– which chemists détermine the relative tinctorial powers of roots, madders, and garancines, but I may give you a very simple method of detecting ordinary adultérations of garancine by dye woods and tannin matters. Pièces of blotting paper are dipped into a weak solution of chloride of tin and sulphate of protoxide of iron, and on each of these sheets is sprinkled a little of the suspected garancine. If a dye wood be présent, the chloride of tin paper will assume a red colour, and if tannin matter be présent, the iron paper will be blackened.
LECTURE II.—Delivered TUESDAY, FEBRUARY 14TH, 1871.
RED COLOURING SUBSTANCES (continued}.— MUNJEET; CAMPECHY, PEACH, SAPAN, CANE, AND BAR WOODS ; ALKANET ROOT ; SAFFLOWER ; COCHINEAL, LAC DYE ; MUREXIDE.
Munjeet.—It is to the researches of Dr. John Stenhouse, one of the most eminent and leamed of English chemists, that we are indebted for our knowledge of the true composition of many of the dye-stuffs, and it is to him that we are indebted for the whole of the information we possess in the colouring matters of munjeet, or Rubia munjista.
This peculiar variety of the genus rubia is cultivated exclusively in Asia, and especially in India, where it has been used as a dye-stuff for a long period of time, either alone or mixed with other dyes, to produce a variety of redshades. It is imported into this country from time to time, but has never been extensively used, as the colours produced from it are neither so fast nor so bright as those obtained with Rubia tinctorum.
Whilst the colouring principles of madder are purpurine and alizarine, those of munjeet are purpurine and a yellow colouring matter, named by Dr. Stenhouse munjistine. He has assigned to this latter body the formula C. H. O6. When crystallized from an alcoholic solution, it forma large, beautiful, golden-coloured flakes, which sublimed, give prismatic crystals of an orange-red colour. It is only slightly soluble in cold water, but freely soluble in hot water. Its beat solvent is bisulphuret of carbon, which was em-ployed with success by Dr. Stenhouse in separating the purpurine and munjistine from the other substances existing in munjeet. He States that the munjeet root contains as much colouring matter as the Rubia tinctorum, and, according to Mr. Higgins, of Manchester, it yields from 52 to 55 per cent, of a garancine ; but as it has only half the dyeing power of ordinary garancine, it cannot be employed with advantage for this purpose. The inferiority of munjeet arises from its containing only the comparatively feeble colouring matters, purpurine and munjistine. Munjeet is not much used by calico printers, as the munjistine gives a brownish-purple with salts of iron, which prevents it being employed with that mordant. It is used for spécial shades of Turkey red, the munjistine giving, with salts of alumina, an orange-yellow colour, which is in some instances employed by the dyers.
I have now the pleasure of calling your attention to an important class of dyeing substances, " the dye-woods.”
Campechy or Logwood.—1This wood, obtained from a large tree of the leguminous family, called by the botanist Hematoxylum campechianum, grows abundantly in the West Indies, Mexico, and other states of South America. The best quality is imported from the Bay of Campechy, in the Gulf of Mexico. Large quantifies are also obtained from Jamaica and St. Domingo. The qualifies obtained from Honduras, Martinique, and Guadaloupe are inferior.
Campechy was introduced into Europe by the Spaniards, but it was not till the reign of Elizabeth that it came into use in England, and then only for a short period, after which its employment was forbidden under the severest penalties for upwards of a century.
The discovery of its colouring principle, hematine, was made in 1810, by my learned and venerable master, M. Chevreul (who, although now 85 years old, is still actively engaged in scientific pur suits). Shortly afterwards it was studied by Ermann, who gave it the name of hematoxyline. It was obtained by these eminent chemists as yellowish white prismatic crystals, which become dis-coloured by contact with the oxygen of the air and the small amount of ammonia which the atmosphère contains. It is only slightly soluble in cold water, but much more so in hot. It is very soluble in alcohol, ether, and bisulphuret of carbon. It combines with three équivalents of water, forming a crystalline hydrate, which at 212° F. retains one équivalent.
Hematine in the presence of oxygen, especially under the influence of alkalies, assumes a beautiful purple colour. This colouring matter can be obtained under the form of purple-black crystals, having a metallic lustre, and has received the name of hcmatëine. Hematine has the formula C, 6 H, 4 08, which, on conversion into hema-tëine, becomes C1H,20.,II,0. The hydrate is C, 6 Hi 06,3 H2O, which at 212” F. becomes C1H1406, H.O.
The oxydation, and conséquent colouration, of hema-
Le texte affiché peut comporter un certain nombre d'erreurs. En effet, le mode texte de ce document a été généré de façon automatique par un programme de reconnaissance optique de caractères (OCR). Le taux de reconnaissance estimé pour cette page est de 97,97 %.
La langue de reconnaissance de l'OCR est le Français.