The urine which is voided when the system is deranged or diseased is altered in its color and composition, showing that its ingredients vary greatly. So important an aid do examinations of the urine furnish in diagnosing many chronic ailments, that at the Invalids' Hotel and Surgical Institute, where many thousands of cases are annually treated, a chemical laboratory has been fitted up, and a skillful chemist is employed, who makes a specialty of examining the urine, both chemically and microscopically, and reporting the result to the attending physicians. His extended experience renders his services invaluable. With his assistance, maladies which had hitherto baffled all efforts put forth to determine their true character, have frequently been quickly and unmistakably disclosed. MICROSCOPICAL EXAMINATION. This method of examination affords a quicker and more correct idea of a deposit or deposits than any other method. The expert, by simply looking at a specimen, can determine the character of the urine, whether blood, mucus, pus, uric acid, etc., are present or not. But when no deposit is present, then it is necessary to apply chemical tests, and in many cases the quantity of the suspected ingredient must be determined by analysis. As a detailed account, of the various modifications which the urine undergoes in different diseases, would be of no practical use to the masses, since they could not avail themselves of the advantages which it would afford for correct diagnosis, except by the employment of a physician who does not ignore this aid in examining his patients, we shall omit all further details upon the subject. For the same reason we shall not often, in treating of the different diseases in which examinations of the urine furnish such valuable aid in forming a diagnosis, make mention of the changes which are likely to have occurred. INFLAMMATION. The term _Inflammation_ signifies a state in which the infected part is hotter, redder, more congested, and more painful than is natural. Inflammation is limited to certain parts, while fever influences the system generally. Inflammation gives rise to new formations, morbid products, and lesions, or alterations of structure. The morbid products of fever, and its modification of fluids are carried away by the secretions and excretions. The susceptibility of the body to inflammation maybe _natural_ or _acquired_. It is natural when it is constitutional; that is, when there is an original tendency of the animal economy to manifest itself in some form of inflammation. We may notice that some children are far more subject to boils, croups, and erysipelatous diseases than others. This susceptibility, when innate, may be lessened by careful medication, although it may never be wholly eradicated. When acquired, it is the result of the influence of habits of life, climate, and the state of mind over the constitution