Problem: Solar distillation can be used to make saline or brackish water potable. The first recorded instance of this was by 16th-century Arab alchemists. A large-scale solar distillation project was first constructed in 1872 in the Chilean mining town of Las Salinas. The plant, which had solar collection area of 4,700 m2 (51,000 sq ft), could produce up to 22,700 L (5,000 imp gal; 6,000 US gal) per day and operate for 40 years. Individual still designs include single-slope, double-slope (or greenhouse type), vertical, conical, inverted absorber, multi-wick, and multiple effect. These stills can operate in passive, active, or hybrid modes. Double-slope stills are the most economical for decentralized domestic purposes, while active multiple effect units are more suitable for large-scale applications.
In what year was a large scale solar distillation project constructed in Las Salinas?
The answer is the following: 1872

Problem: Meetings for worship and study are held at Kingdom Halls, which are typically functional in character, and do not contain religious symbols. Witnesses are assigned to a congregation in whose "territory" they usually reside and attend weekly services they refer to as "meetings" as scheduled by congregation elders. The meetings are largely devoted to study of Watch Tower Society literature and the Bible. The format of the meetings is established by the religion's headquarters, and the subject matter for most meetings is the same worldwide. Congregations meet for two sessions each week comprising five distinct meetings that total about three-and-a-half hours, typically gathering mid-week (three meetings) and on the weekend (two meetings). Prior to 2009, congregations met three times each week; these meetings were condensed, with the intention that members dedicate an evening for "family worship". Gatherings are opened and closed with kingdom songs (hymns) and brief prayers. Twice each year, Witnesses from a number of congregations that form a "circuit" gather for a one-day assembly. Larger groups of congregations meet once a year for a three-day "regional convention", usually at rented stadiums or auditoriums. Their most important and solemn event is the commemoration of the "Lord's Evening Meal", or "Memorial of Christ's Death" on the date of the Jewish Passover.
Where do Jehovah Witnesses meet for worship and study?
The answer is the following: Kingdom Halls

Problem: Where every component state of a federation possesses the same powers, we are said to find 'symmetric federalism'. Asymmetric federalism exists where states are granted different powers, or some possess greater autonomy than others do. This is often done in recognition of the existence of a distinct culture in a particular region or regions. In Spain, the Basques and Catalans, as well as the Galicians, spearheaded a historic movement to have their national specificity recognized, crystallizing in the "historical communities" such as Navarre, Galicia, Catalonia, and the Basque Country. They have more powers than the later expanded arrangement for other Spanish regions, or the Spain of the autonomous communities (called also the "coffee for everyone" arrangement), partly to deal with their separate identity and to appease peripheral nationalist leanings, partly out of respect to specific rights they had held earlier in history. However, strictly speaking Spain is not a federalism, but a decentralized administrative organization of the state.
What does every component state of federation possess?
The answer is the following: the same powers

Problem: The city also had a large class of free people of color. By 1860, 3,785 free people of color were in Charleston, nearly 18% of the city's black population, and 8% of the total population. Free people of color were far more likely to be of mixed racial background than slaves. Many were educated, practiced skilled crafts, and some even owned substantial property, including slaves. In 1790, they established the Brown Fellowship Society for mutual aid, initially as a burial society. It continued until 1945.
How many free people of color lived in Charleston in 1860?
The answer is the following:
3,785