Few engineering topics are at present discussed witli greater ability than those connected with the disposal of sewage. Our readers have been frequently posted by us, in regard to the end desirable to be attained; namely, the disposal of sewage so that it can bo utilized as fertilizing material, or in some manner that will not tend to impair the public health, or comfort. Among the best of the labored articles upon this subject we have perused is one entitled " A Chemist's view of the Sewage Question," by Edward C. C. Stamford, F. C. S., published in the Clicmical News. Mr. Stamford clearly shows in his essay that the problem cannot be solved upon merely mechanical data. He says; "Thepresent water closet system, with all its boasted advantages is the worst that can be generally adopted, briefly because it is a most extravagant method of converting a mole-hill into a mountain. It merely removes the bulk of our excreta from our houses, to choke our rivers with foul deposits and rot at our neighbors' doors. It increases the death rate, as well as all other rates, and introduces into our houses, a most deadly enemy, in the shape of sewer gases." Mr. Stamford, predicts that the water closet will be ultimately doomed to oblivion. He reviews the process of Mr. Chapman, one of the latest proposed methods of dealing with town sewage, which is briefly a process of distillation, after treatment with lime and thorough putrefaction, points out important defects, and decides that its effectiveness is to say the least problematical. The xirocess of Mr. Glassford, evaporation with sulphuric acid, he deems far more certain. But both these methods are connected r,ith the water system and this Mr. Stamford considers a radical defect. The dry earth system of Moule, he considers the most hopeful of any yet proposed. The question of removal of sewage is not the only ono that is to be considered, what to do with it after it is removed is the most puzzling part of the problem and is strictly a chemical question. The Moule earth system is the only one that has taken into full account the chemical bearings of the question and has dealt with it in a simple and practical manner. It at once provides for disposal and removal, making the former the prime object. Mr. Stamford in order to obviate a difficulty which seems to us purely imaginary, namely the difficulty of obtaining a sufficient supply of pare dry earth, proposes to substitute seaweed charcoal, a pov.'eiful absorbent. Now so far as this is Cjucerned we believe there will ultimately bo no difficulty in obtaining earth for the purpose, but if tho sj-stem should become general, the privilege of furnishing earth and taking iJ.way tlie resulting compost will be so valued as to make it a s'.ibject of solicitation : perhaps e-en a commercial value will b.come fxcd to the compost, and we may live to see tlie time when it will be found quoted in commercial price lists with guano and other fertilizers. The amount of earth required is only three and one half times the weight of the excreta, and as seaweed charcoal, though only one fourth as much would be required, would certainly cost more than earth, the latter could never compete with the former except on shipboard, or in cases where largo bodies of earth must be transported unless the charcoal Cftuld be in some way renovated and its absorbent power restored. As charcoal can be used over several times, and then redistilled with the mixed excreta, the whole ammonia product being recovered, and the charcoal thus renovated recovers its absorbent power, it may be that the system of Mr. Stamford will be found to possess some advantages. Mr. Stamford has made some interesting researches on the products of the distillation of the mixed charcoal and excreta. These products are, he finds, remarkably similar in composition to the distillates from bones, in manufacturing bone-black. Ammonia, acetic acid, butyric acid, acetone, and pyrol are the most marked products, and the charcoal produced is, he asserts second only in value to that of bones. The redistilled seaweed charcoal, and the charcoal resulting from the destructive distillation of the excreta will give an increased weight of charcoal, so that if this process were adopted, the product for the city of Glasgow alone, it is estimated would be nineteen tuns per day. The uses to which this charcoal might be applied are various. The system seems to have been the result of much study and close thought, but we doubt whether its merits will ever prove so great as to supersede the dry earth method.
This article was originally published with the title "The Sewage Question"