The acid is useful in the vomiting of fever, and in sympathetic vomiting, and is sometimes indicated in that of ordinary gastric derangement: it may be added to effervescent mixtures, or to bismuth, but as a rule is better given alone in distilled water. In some patients, or in some conditions, and more especially when the dose is too large, nausea and vomiting seem to be increased or caused by the drug, and then it is better omitted: on the other hand, I have seen severe cases recover with 6 to 8 min. doses, when smaller doses and all ordinary means had failed. In simple intestinal obstruction, even when faecal vomiting had occurred, I have used 10 min. doses with the effect of staying the vomiting, but care is necessary in watching the results. Dr. Brinton found the acid useful in the vomiting of gastric ulcer; Dr. Harley combined it with bismuth, opium, etc., in that of enteric fever; Pereira recommended it in the vomiting and purging of phthisis, and even of cholera, and it may well be tried in the "nervous" form of vomiting, that connected with pregnancy, or with cerebral concussion or disorder.