When phenothiazine concentrates are administered with the diluting agents recommended by the manufacturers, precipitates may be formed which are sometimes colored. These render the mixture unpalatable and the patient may not ingest the full amount of the phenothiazine prescribed. It is possible that some of the compounds formed are reverted to their original form by the gastric acidity. However, some do appear to be permanently insoluble.As a result of these studies, it appears that, ideally, the phenothiazine concentrates should be given diluted with freshly distilled water only. When this method of administration was tried on two wards, patient acceptance was varied and was dependent upon the taste of the vehicle and the total amount of phenothiazine involved.