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COMMENTARY
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they also show the confusion that was caused when the ancients failed to see that each of these substances had distinctive properties of its own. However, the confusion in this treatise may also have arisen because Theophrastus had no first-hand information.
65. it is used on buildings and is poured around the stone or anything else of this kjnd that one wishes to fasten. Here gypsos appears to mean a prepared mortar, and unless this statement applies to a very dry country like Egypt, die material must be lime mortar and not gypsum mortar, since the latter soon disintegrates in wet weather. Though only a few chemical analyses have been made of ancient Greek mortars, they indicate that lime mortar was the only kind used in Greece at the time of Theophrastus.506
66. After it has been pulverized and water has been poured on it, it is stirred with wooden sticks; for this cannot be done by hand because of the heat.
Though both quicklime and dehydrated gypsum generate heat when mixed with water, quicklime generates far more heat. Since Theophrastus makes a point of mentioning the heat, it is likely that he is referring to mortar made from quicklime and not to gypsum mortar. It is curious that Theophrastus says nothing about the addition of sand or any other filler, since a satisfactory mortar could not have been made without this. Foster's analyses507 show that the Greeks added about one part of sand to two parts of lime in the preparation of their mortars. Since Theophrastus says nothing about any filler, it is probable that he had no first-hand knowledge of the subject.
66. And it is wetted immediately before it is used; for if this is done a short time before, it quichjy hardens and it is impossible to divide it.
This sentence differs sharply in significance from the two that precede it, for it indicates that Theophrastus is now speaking of gypsum plaster or mortar, which, in contrast to a lime preparation,
506 Foster, Journal of Chemical Education, XI (1934), 223-24. 607 Loc. at.
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