160 LECTURES. 



prepared lime. Dr. Reid had used tliis largely in many buildings 

 occu])ied soon after completion, ttistriljuting, in one case, cart loads of 

 quicklime in the air channels and in the dilFerent apartments where 

 the pressure of public business induced the authorities to occupy courts 

 of law the day after very extensive alterations had been com})leted, 

 without waiting either for the drying of tlie plaster in the usual man- 

 ner, or for painting and decorations. When a building was sur- 

 rounded with an external malarious atmosphere, by a right system of 

 drainage this could in general be removed, at least from the immedi- 

 ate vicinity. Where the drainage was not sufficient, an active system 

 of vegetation became the next resource. If temporary or other causes 

 prevented this being carried to a proper extent, the antiseptic power of 

 caustic lime could be applied with great success. He was prej)ared to 

 point out many opportunities where this agent ought to be used in all 

 cities he liad hitherto examined. Numerous other chemicals could be 

 rendered available, particularly clioride of lime, muriate of zinc, and 

 other substances. Their elfects were seldom, however, obtained to the 

 extent they were capable of producing, from a want of knowledge on the 

 part of those who applied them of the chemical details essential to 

 their full 0})eration. Where vitiated emanations were traced within 

 a building to any special drain, close chamber, room, or other space, 

 either in the basement or elsewhere, a special ventilating power 

 should be brouglit to bear on them in the same manner as the venti- 

 lating shaft exhibited had been brought to act upon all the mate- 

 rials used in the illustrations given at the experimental table, unless 

 the cause was altogether temporary and easily removed. 



FOURTH LECTURE. 



The ventilation of individual rooms and habitations formed the 

 most important question connected with sanitary improvements. These 

 were the phices where the great mass of mankind si)entthe larger por- 

 tion of their time; where they were born and where they died ; there 

 they generally spent the period of their infancy and childhood, wheir 

 days of suffering and sickness, and recruited their daily strength with 

 food and by reposing from their labors. A vitiated atmosphere at home 

 corrupted the condition of the blood more than any other cause, inas- 

 much as it had a more continuous })ower of operation. The effect of 

 each .individual inspiration might indeed be trifling, but when re- 

 peated twelve hundred times an lionr for days, and montlis, and years, 

 and brought in direct action upon the blood itself in the lungs, it was 

 to be expected t-liat it should soon affect every fibre of the living frame. 



In studying the ventilation of individual rooms and habitations, 

 it was recommended that the rotatory movements of air in a confined 

 atmos])here sliould be examined when an inequality of temperature 

 was induced, and that these movements should be rendered ])a!i)able 

 by elieniieals |)roducing heat and smoke. Franklin had made use of 

 this expedient, and had it been more generally attended to, ventilation 

 would have made much more progress than it had done. Experi- 



