| 摘要 |
The invention relates to acid crystals the surface of which consists at least partially of a dehydrated water soluble salt. The preparation thereof is characterized in that the acid crystals are mixed with a metal oxide or hydroxide and the obtained mixture is reacted under substantially anhydrous conditions in the presence of traces of water. These modified crystals are very suitable to use as the acidic component in various mixtures, e.g. in effervescent mixtures, as these crystals can absorb some moisture without starting the carbon dioxide development. Tablets containing the acid crystals of the invention are hard when freshly prepared and show the tendency to gain in hardness on exposure to the atmosphere for some days. Moreover they are completely water-soluble with a delayed acid release.
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