Soldering other precipitation may wash the lead into the groundwater. Unfortunately, most lead-free solders are not eutectic formulations, melting at around , making it more difficult to create reliable joints with them. Other common solders include low-temperature formulations (often containing bismuth), which are often used to join previously-soldered assemblies without unsoldering earlier connections, and high-temperature formulations (usually containing silver) which are used for high-temperature operation or for first assembly of items which must not become unsoldered during subsequent operations. Alloying silver with other metals changes the melting point, adhesion and wetting characteristics, and tensile strength. Of all the brazing alloys, silver
Hard and soft C or an alveolo-palatal , and occurs before not only , and , but also , , and . Another similar system with hard and soft is found in Faroese with the hard being and the soft being , and Turkish where the soft is . The Vietnamese alphabet does not have a hard or a soft per se. However, since it was inherited from European languages, the letter never occurs in "soft positions", i.e. before , and where is used instead, while never occurs elsewhere except in the digraph and a few loanwords. Hồ Chí Minh had proposed a simplified