Volume 1

Report on water supply and sewerage.

  • Massachusetts. State Board of Health.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Report on water supply and sewerage. Source: Wellcome Collection.

    30/894 (page 4)
    matters and sediment, while the figures in heavy-faced type indicate determina- tions made on the water after it has been filtered through paper in the laboratory. A few cases will be noted in the tabulated results, in which one or more chemical determinations differ somewhat widely from others in the same series. Such a condition of the water might result from floods or ether unusual disturbance of a stream, or from carelessness in collection, or an error may have been made in the analysis. In such cases the determination has been underlined and has not been included in the averao;e. Where the determinations of the loss on io:nition and fixed residue are underlined, the coiTesponding total residue is omitted from the average. Ko attempt has been made to give the character of the waters in connection with the tabulated results of the analyses. In the subsequent general discussion of the water supplies, the qualities and peculiarities of many of the waters will be referred to more or less at length. For the characters of those waters which are not especially mentioned in this discussion, the reader is referred to that por- tion of the rej)ort which (^eals with the “ interpretation of analyses.” In addition to the determinations given in the tables each sample has been examined for its odor, both cold and hot. The complete record of these odors it was thought unnecessary to include in the table, but mention of their general character is made in the foot-note after the chemical results. The hardness of the waters has been determined once for each water, and is given in the foot-note. The appearance and odor on ignition of the solid residue of evaporation was also determined in each sample, but this record is not in the tables, since the significance of these determinations is, in most waters, of subordinate importance. The color of the waters is expressed by numbers which increase with the amount of color. Water having a color of 1.0 is a decided 3’ellowish brown when seen in small bulk, as in a tumbler. As a standard of comparison, it may be mentioned that the color of water from the Cochituate works, as drawn from a tap at the Massachusetts Institute of Technolog^^ is generally about 0.35. The “ loss on ignition ” is not given in the analyses of ground waters, since it bears little or no relation to the amount of organic matter present in the water. This subject will be fully discussed in the section of the report devoted to “ meth- ods of analysis.” Averages have been made of the chemical determinations in the tables as a matter of convenience for those who wish to study the results. In many cases the averages are for a less period than a year, and in others for a period between one and two years. In these cases the averages cannot, obviously, express a mean yearly composition of the water. The averages of the determinations ex- pressed in heavy-faced type are not given except when these determinations have been made for all samples in the table. The microscopical examination of water from a few sources was begun in July, 1887 ; but the systematic examination of all the waters was not undertaken until March, 1888. After this time a sample for microscopical examination was taken from each bottle of water received at the chemical laboratory. The standard quantity of water used in an examination was 200 cubic centimetres. From March 16 to June 5,1888, the quantitative estimate of the organisms was expressed b^^ adjectives indicating their relative abundance. Since June 5, 1888, greater care has been taken to determine the number of organisms of each kind removed by filtration from the 200 cubic centimetres of