Facts Keeping hydrated is crucial for health and well-being, but many people do not consume enough fluids each day. Around 60 percent of the body is made up of water, and around 71 percent of the planet's surface is covered by water. Perhaps it is the ubiquitous nature of water that means drinking enough each day is not at the top of many people's lists of priorities.
The early history Although alum is not specifically relevant to the development of wove paper, this chemical was used by the Whatmans in the production of their celebrated high quality papers, made during the 18th C.
Provided papers like these have not been exposed to a hostile environment during the two hundred and fifty years following their manufacture, we find that they are as robust as ever they were, and some much more so than many papers made today.
Indeed the same applies to most other top quality papers made in this and other countries in the 16th and 17th Cs. And yet, nowadays, for some reason the presence of alum in paper is regarded as undesirable, even harmful.
The questions posed by this are, does alum deserve this reputation? What is its function in papermaking?
And, finally, are we absolutely clear what "alum" is? In papermaking the distinction between "alum" and hydrated aluminium sulphate has become blurred during the transition from the one substance to the other over the last hundred years.
In fact Labarre Bib. To help us answer these questions, a very condensed history of the chemical follows, with a description of the process used in its manufacture in England during the period covered by this book, for which due acknowledgment is made to Professor Singer's great monograph and to more recent work carried out by members of the Cleveland Industrial Archaeology Society; see Footnotes and Bibliography.
The early history of alum The procurement of alum has been dubbed "The earliest Chemical Industry" by Professor Charles Singer in a monumental study of its occurrence and of its manufacture in the past Bib. There are oblique references to alum, sometimes very obscure, dating back at least to two millennia B.
But the certainty of its actual usage can only be proved by analysing and dating artefacts in which alum had been employed at some stage of their creation, undoubtedly an activity of even greater antiquity.
It was used mainly for mordanting; for tanning and softening leather; for its alleged medicinal and cosmetic properties; and as an auxiliary agent in miscellaneous metal and glass finishes.
Alum occurs naturally in more than one form; but, where it was not readily available, it had to be manufactured. The processes involved ranged from relatively simple methods to extremely sophisticated ones.
In principle the latter made use of certain sedimentary aluminium bearing rocks or shales which were converted by various means to yield aluminium sulphate, which, in turn, was converted into alum, usually as the ammonium or potassium double salt.
They do not identify "alum" specifically, but, as mentioned above, its presence can be deduced from the things for which it was used, both in its local application and from those found in other countries, e. By the 5th C. The Ancients had discovered that alum possessed certain valuable qualities not found together in any other common substance: Its sources were, therefore, identifiable with relative ease.
Singer has pointed out, "that alum was obtainable pure was thus a technical accident and not the result of any considered rational plan or of any refined system of manufacture". The sophisticated methods of manufacture, referred to above, took millenia to evolve.
The process that is of most interest to us in the present context, the one used in the alum industry of North Yorkshire, has been described as "a marvel of empirical industrial chemistry".
The Greek, Roman, Byzantine and Arabian civilizations were all involved, together with other sources of influence, penetrating this world from India and, by the silk route, from China. For detailed information on the effect they had on the supply and use of alum, reference must be made to Singer's monograph.
It was from all the sources mentioned above that the first methodical statements on the nature of alum were derived. The findings are set out in 8thth C.
By this time the Arabs had conquered the whole of North Africa and thus confronted, and even penetrated, the southern borders of Europe. Trade links between the two were strong and there was no shortage of European scholars who were able to read arabic and assimilate its learning.
It might be noted at this juncture that it was just after this period that papermaking was undertaken for the first time by Europeans, albeit the use of alum in this activity lay sometime in the future.
The demand for alum from countries to the north of the Mediterranean was an ancient one; but from the 10thth Cs.
The sources of supply were various. Some European countries favoured supplies from Sicily and the Aeolian islands; Spain had its own resources, with especially high quality coming from Castile; but the best qualities still came from the Middle East. The four Crusades of the 12th C.
For one thing, the last crusade helped polarize the antagonism of the Roman and Eastern churches. Meanwhile new agencies were affecting this situation.
The Mongols sacked Baghdad in shattering Arabian culture at its source; the Turks were beginning to dominate the middle eastern scene; and, equally important for the future development of alum supplies, the City States of northern Italy were transforming and widening the market. They included, initially, the Venetian Republic, Genoa and Pisa.
Pisa, however, soon succumbed to the expanding power of Florence. Genoa not only built up lasting trade links with north-western Europe, e.This lesson describes the function and importance of the sodium potassium pump. It contains real-world examples and an illustration to guide your understanding.
Essay Radioactive Wastes Radioactive wastes, must for the protection of mankind be stored or disposed in such a manner that isolation from the biosphere is assured until they have decayed to innocuous levels.
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